Systems and methods for processing and transmitting sensor data

ABSTRACT

Systems and methods for processing, transmitting and displaying data received from an analyte sensor, such as a glucose sensor, are provided. The data can be displayed on a hand-held display device having a display such as a key fob device including a user interface, such as an LCD and one or more buttons  604  allows a user to view data, and a physical connector, such as USB port.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119(e) of U.S.provisional application Ser. No. 61/538,447, filed Sep. 23, 2011, thedisclosure of which is hereby expressly incorporated by reference in itsentirety and is hereby expressly made a portion of this application.

FIELD

The present invention relates generally to systems and methods forprocessing, transmitting and displaying data received from an analytesensor, such as a glucose sensor.

BACKGROUND

Diabetes mellitus is a disorder in which the pancreas cannot createsufficient insulin (Type I or insulin dependent) and/or in which insulinis not effective (Type 2 or non-insulin dependent). In the diabeticstate, the victim suffers from high blood sugar, which causes an arrayof physiological derangements (kidney failure, skin ulcers, or bleedinginto the vitreous of the eye) associated with the deterioration of smallblood vessels. A hypoglycemic reaction (low blood sugar) may be inducedby an inadvertent overdose of insulin, or after a normal dose of insulinor glucose-lowering agent accompanied by extraordinary exercise orinsufficient food intake.

Conventionally, a diabetic person carries a self-monitoring bloodglucose (SMBG) monitor, which typically requires uncomfortable fingerpricking methods. Due to the lack of comfort and convenience, a diabeticwill normally only measure his or her glucose level two to four timesper day. Unfortunately, these time intervals are spread so far apartthat the diabetic will likely find out too late, sometimes incurringdangerous side effects, of a hyperglycemic or hypoglycemic condition. Infact, it is not only unlikely that a diabetic will take a timely SMBGvalue, but additionally the diabetic will not know if his blood glucosevalue is going up (higher) or down (lower) based on conventionalmethods.

Consequently, a variety of non-invasive, transdermal (e.g.,transcutaneous) and/or implantable electrochemical sensors are beingdeveloped for continuously detecting and/or quantifying blood glucosevalues. These devices generally transmit raw or minimally processed datafor subsequent analysis at a remote device, which can include a display.

SUMMARY

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

In a first aspect is provided a method for transmitting data between afirst communication device associated with an analyte sensor and asecond communication device configured to provide user access to analytevalues and/or information derived from analyte values, comprising:activating a transceiver of a first communication device associated withan analyte sensor at a first time; establishing a two-way communicationchannel with the second communication device using an authenticationscheme; sending analyte sensor data to the second communication deviceusing the two-way communication channel; deactivating the transceiver ofthe first communication device at a second time; and periodicallyrepeating the activating, establishing, sending and deactivating,wherein a difference between the first time and the second time is lessthan or equal to one minute, and wherein the periodic repeating isperformed at least once every 30 minutes.

In an embodiment of the first aspect, activating comprises supplyingpower to the transceiver, and wherein deactivating comprises poweringdown the transceiver.

In an embodiment of the first aspect, activating comprises waking thetransceiver from a low power sleep mode, and wherein deactivating thetransceiver comprises placing the transceiver into a lower power sleepmode.

In an embodiment of the first aspect, the method further comprisesclosing the two-way communication channel before deactivating thetransceiver.

In an embodiment of the first aspect, the difference between the firsttime and second time corresponds to a transmission time window, andwherein the analyte sensor data corresponds to a new glucose measurementobtained prior to a beginning of the time window, and wherein beginningsof successive time windows are separated by an update time interval.

In an embodiment of the first aspect, the method further comprisesperiodically measuring an analyte sensor value before each of theperiodic repeating the activating, establishing, sending, anddeactivating.

In an embodiment of the first aspect, the analyte sensor value comprisesa glucose concentration.

In another aspect related to the first aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the first aspect and/or any one or more of itsembodiments, wherein the system comprises a sensor electronics moduleincorporating a transceiver, the sensor electronics module configured toelectronically couple to an analyte sensor and generate an analyte datastream using the analyte sensor.

In a second aspect is provided a method for authorizing analyte sensordata exchange between a first communication device associated with ananalyte sensor and a second communication device configured to provideuser access to analyte values and/or information derived from analytevalues, comprising: sending a challenge value from a first communicationdevice associated with an analyte sensor to a second communicationdevice; generating a first hash value in the second communication deviceusing, at least in part, one or more of the challenge value, anidentifier of the first communication device, or a key value; sendingthe first hash value from the second communication device to the firstcommunication device; generating, using the first communication device,a second hash value and a third hash value; comparing, using the firstcommunication device, the second hash value and the third hash values tothe first hash value; and sending analyte sensor data only if at leastone of the second hash value or the third hash values matches the firsthash value.

In an embodiment of the second aspect, the method further comprisesdetermining a type of the second communication device based on a matchbetween the first hash value and the second hash value or a matchbetween the first hash value and the third hash value.

In an embodiment of the second aspect, the key value is a first value ifthe second communication device is of a first type, and wherein the keyvalue is a second value if the second communication device is of asecond type.

In an embodiment of the second aspect, the type of second devicecorresponds to one of a primary device or a secondary device, whereinthe primary device is configured to communicate analyte calibration datato the first communication device, and wherein the first communicationdevice is configured to reject analyte calibration data received from asecondary communication device.

In an embodiment of the second aspect, the first hash value is generatedusing a display identifier.

In an embodiment of the second aspect, sending analyte sensor datacomprises sending analyte sensor data based at least in part on the typeof the second communication device.

In another aspect related to the second aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the second aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, and wherein the sensor electronics module isconfigured to electronically couple to an analyte sensor and to generatean analyte data stream using the analyte sensor.

In a third aspect is provided a method for transmitting data between afirst communication device associated with an analyte sensor and one ormore second communication devices configured to provide user access toanalyte values and/or information derived from analyte values,comprising: receiving a request from a second communication device ofthe one or more second communication devices to establish a channel forreceiving analyte sensor data from the first communication device duringa transmission window; and establishing a communication channel betweenthe first communication device and the second communication device if anumber of communication devices that previously received analyte sensordata from the first communication device during the transmission windowis below a threshold.

In an embodiment of the third aspect, the second communication devicecomprises a secondary communication device.

In an embodiment of the third aspect, the method further comprises:determining whether the second communication device is a primarycommunication device; and establishing, if the second communicationdevice is a primary communication device, a communication channel withthe second communication device even if a number of communicationdevices that previously received analyte sensor data during thetransmission window is equal to or greater than the threshold.

In another aspect related to the third aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the third aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and to generate an analytedata stream using the analyte sensor.

In a fourth aspect is provided a method for transmitting data between afirst communication device associated with an analyte sensor and one ormore second communication devices configured to provide user access toanalyte values and/or information derived from analyte values,comprising: establishing a communication channel only with a primarydevice of a one or more second communication devices during a first timeperiod within a communication window; and establishing a communicationchannel with one or more secondary devices of the one or more secondcommunication devices only during a second time period different fromthe first time period.

In another aspect related to the fourth aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the fourth aspect and/or any one or more of itsembodiments, comprising a sensor electronics module configured toestablish a communication channel with a primary device and establishingthe communication channel with one or more secondary devices.

In a fifth aspect is provided a method for synchronizing a time fortransmitting data between a first communication device associated withan analyte sensor and a primary communication device and a secondarycommunication device configured to provide user access to analyte valuesand/or information derived from analyte values, the method comprising:receiving a beacon from a first communication device at a primarycommunication device during a transmission time window defined by thefirst communication device; establishing a first communication channelbetween the primary communication device and a secondary communicationdevice; transmitting beacon information from the primary communicationdevice to the secondary communication device, wherein the beaconinformation comprises timing information for establishing acommunication channel with the first communication device; andestablishing a communication channel between the first communicationdevice and the secondary communication device based on the beaconinformation.

In an embodiment of the fifth aspect, establishing a first communicationchannel between the primary communication device and the secondarycommunication device comprises executing an authentication protocolbetween the primary communication device and the secondary communicationdevice.

In an embodiment of the fifth aspect, the first communication device isconfigured to periodically send the beacon in a series of periodictransmission time windows separated by an update time interval.

In an embodiment of the fifth aspect, the timing information comprisesinformation about a time corresponding to the start of the transmissiontime window.

In another aspect related to the fifth aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the fifth aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and generate an analyte datastream using the analyte sensor.

In a sixth aspect is provided a method for processing data from ananalyte sensor and transmitting data between a first communicationdevice associated with an analyte sensor and a second communicationdevice configured to provide user access to analyte values and/orinformation derived from analyte values, comprising: activating ananalyte sensor data processing circuit and deactivating a transceiver ofa first communication device associated with an analyte sensor during afirst time interval; obtaining and processing analyte sensor data duringthe first time interval; deactivating the analyte sensor data processingcircuit and activating the transceiver of the first communication deviceduring a different second time interval; and transmitting analyte sensordata to the second communication device during the second time interval.

In an embodiment of the sixth aspect, activating and deactivating theanalyte sensor data processing circuit comprises powering-up andpowering-down the analyte sensor data processing circuit.

In an embodiment of the sixth aspect, activating and deactivating theanalyte sensor data processing circuit comprises activating anddeactivating a low power mode of the analyte sensor data processingcircuit.

In an embodiment of the sixth aspect, activating and deactivating thetransceiver comprises powering-up and powering-down the transceiver.

In an embodiment of the sixth aspect, activating and deactivating thetransceiver comprises activating and deactivating a low power mode ofthe transceiver.

In another aspect related to the sixth aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the sixth aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor.

In a seventh aspect is provided a method for processing data from ananalyte sensor, comprising: obtaining and processing analyte sensor datausing an analyte sensor data device associated with an analyte sensorduring a first time interval; opening a transmission time window toaccept requests for establishing a communication channel to communicateto the analyte sensor data device during a different second timeinterval, wherein the first time interval and the second time intervaldo not overlap.

In another aspect related to the seventh aspect, a system is providedfor monitoring an analyte level of a host, the system configured toperform the method of the seventh aspect and/or any one or more of itsembodiments, wherein the first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and generate an analyte datastream using the analyte sensor.

In an eighth aspect is provided a method for providing analyte sensormeasurements from a first communication device associated with ananalyte sensor to a second communication device configured to provideuser access to analyte values and/or information derived from analytevalues, the method comprising: receiving, from the first communicationdevice, a request from a second communication device for previousanalyte sensor measurements in addition to analyte sensor measurementsof a scheduled analyte sensor measurement transmission; and transmittingto the second communication device from the first communication device adata set of analyte sensor measurements corresponding to apre-determined time interval that includes the requested previousanalyte sensor measurements.

In an embodiment of the eighth aspect, the previous analyte sensormeasurements comprise a sub-set of the data set of analyte sensormeasurements.

In an embodiment of the eighth aspect, the pre-determined time intervalcorresponds to a twenty-four hour period of analyte sensor measurements.

In another aspect related to the eighth aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the eighth aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and generate an analyte datastream using the analyte sensor.

In a ninth aspect is provided a method for transmitting data between afirst communication device associated with an analyte sensor and aprimary communication device and a secondary communication deviceconfigured to provide user access to analyte values and/or informationderived from analyte values, comprising: establishing a communicationchannel between a secondary communication device and a firstcommunication device during a transmission time window of a sensorsession; determining whether a primary communication device haspreviously been in communication with the first communication deviceduring the sensor session; and rejecting requests for data or commandssent by the secondary communication device to the first communicationdevice if the primary communication device has not been in communicationwith the first device during the sensor session.

In an embodiment of the ninth aspect, the communication between theprimary communication device and the first communication devicecomprises control information for initiating a sensor session.

In another aspect related to the ninth aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the ninth aspect and/or any one or more of itsembodiments, wherein the first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and to generate an analytedata stream using the analyte sensor.

In a tenth aspect is provided a method of transmitting data between afirst communication device associated with an analyte sensor and aprimary communication device and a secondary communication device, eachof the primary communication device and the secondary communicationdevice configured to provide user access to analyte values and/orinformation derived from analyte values, comprising: determining whethera first communication channel has been established between a firstcommunication device and a primary communication device during a timewindow; and establishing a second communication channel between thefirst communication device and a secondary communication device duringthe time window only if the first communication channel was establishedduring the time window.

In another aspect related to the tenth aspect, a system is provided formonitoring an analyte level of a host, the system configured to performthe method of the tenth aspect and/or any one or more of itsembodiments, wherein the first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and generate an analyte datastream using the analyte sensor.

In an eleventh aspect is provided a method for transmitting data betweena first communication device associated with an analyte sensor and asecond communication device configured to provide user access to analytevalues and/or information derived from analyte values, comprising:switching a first communication device between a plurality oftransmission window states, the plurality of window transmission modesincluding: a first transmission window state in which the firstcommunication device does not open a transmission window, a secondtransmission window state in which the first communication deviceperiodically opens a transmission window at a first frequency, and athird transmission window state in which the first communication deviceperiodically opens a transmission window at a second frequency that isless than the first frequency; and transmitting one or more beaconsduring each transmission window state.

In an embodiment of the eleventh aspect, the first communication deviceswitches from the first transmission window state to the secondtransmission window state upon actuation of a hall-effect switch or areed switch.

In an embodiment of the eleventh aspect, wherein the first communicationdevice automatically switches from the second transmission window stateto the third transmission window state responsive to a determination ofa successful pairing of the first communication device with the secondcommunication device.

In an embodiment of the eleventh aspect, the first communication deviceautomatically switches from the second transmission window state to thethird transmission window state responsive to a determination of nosuccessful pairing after a predetermined amount of time since switchingfrom the first transmission window state to the second transmissionwindow state.

In an embodiment of the eleventh aspect, the first frequency is about 30seconds and the second frequency is about 5 minutes.

In another aspect related to the eleventh aspect, a system is providedfor monitoring an analyte level of a host, the system configured toperform the method of the eleventh aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, wherein the sensor electronics module is configuredto electronically couple to an analyte sensor and generate an analytedata stream using the analyte sensor.

In a twelfth aspect is provided a method for transmitting data between afirst communication device associated with an analyte sensor and secondcommunication device configured to provide user access to analyte valuesand/or information derived from analyte values, the method comprising:storing technical support data in a log file in memory in a firstcommunication device; determining that a second communication deviceshould receive at least some of the stored technical support data;transmitting, using the first communication device, a message indicativeof the determination; receiving a request from the second communicationdevice for at least some of the stored technical support data responsiveto the transmitted message; and transmitting the at least some of thestored technical support data.

In an embodiment of the twelfth aspect, the message is included in abeacon transmitted by the first communication device.

In an embodiment of the twelfth aspect, the message consists of a bit.

In another aspect related to the twelfth aspect, a system is providedfor monitoring an analyte level of a host, the system configured toperform the method of the twelfth aspect and/or any one or more of itsembodiments, wherein a first communication device comprises a sensorelectronics module, wherein the sensor electronics module is configuredto electronically couple to an analyte sensor and generate an analytedata stream using the analyte sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating one embodiment of a continuous analytesensor system including a sensor electronics module.

FIG. 2A is a perspective view of a sensor system including a mountingunit and sensor electronics module attached thereto according to oneembodiment.

FIG. 2B is a side view of the sensor system of FIG. 2B.

FIG. 3 is an exemplary block diagram illustrating various elements ofone embodiment of a continuous analyte sensor system and display device.

FIG. 4A is a flow diagram of an exemplary communication between ananalyte sensor system and a display device for communicating glucosemeasurement values.

FIG. 4B is a timing diagram of en exemplary sequence for establishing acommunication channel between an analyte sensor system and a displaydevice.

FIG. 5 is a flowchart of an exemplary method for sending glucosemeasurement values from an analyte sensor system to a display device.

FIG. 6A provides an example of mapping an alphanumeric character to afive bit binary value.

FIG. 6B provides an example of mapping a 35 bit value to a device numberand a transmitter ID.

FIG. 7 is a flowchart illustrating one embodiment of an aspect of aprocess for pairing a transmitter with a receiver.

FIG. 8 is flowchart of an exemplary method for establishing anauthenticated communication channel between an analyte sensor system anda primary or secondary display device.

FIG. 9 is a timing diagram showing an exemplary scheme for exchangingdata between an analyte sensor system and a plurality of displaydevices.

FIG. 10 is a flowchart of an exemplary method for communication betweenan analyte sensor system and a secondary display device.

FIG. 11 is a flow chart of an exemplary method for providing sensortransmission time window information from primary display device to asecondary display device.

FIG. 12A is a timing diagram of an exemplary timing scheme fortransmitting data and obtaining and processing analyte sensormeasurements.

FIG. 12B is a flowchart of an exemplary method for interleaving ananalyte sensor measurement and processing period with a datacommunication period for transmitting glucose measurement values.

FIG. 13A shows an example of data structures that may be stored on ananalyte sensor system that include glucose measurement values.

FIG. 13B is a flowchart of an exemplary method of transmitting sensordata from an analyte sensor system to a display device.

DETAILED DESCRIPTION

The following description and examples illustrate some exemplaryembodiments of the disclosed invention in detail. Those of skill in theart will recognize that there are numerous variations and modificationsof this invention that are encompassed by its scope. Accordingly, thedescription of a certain exemplary embodiment should not be deemed tolimit the scope of the present invention.

DEFINITIONS

In order to facilitate an understanding of the systems and methodsdiscussed herein, a number of terms are defined below. The terms definedbelow, as well as other terms used herein, should be construed toinclude the provided definitions, the ordinary and customary meaning ofthe terms, and any other implied meaning for the respective terms. Thus,the definitions below do not limit the meaning of these terms, but onlyprovide exemplary definitions.

The term “analyte” as used herein is a broad term and is to be given itsordinary and customary meaning to a person of ordinary skill in the art(and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to a substance or chemicalconstituent in a biological fluid (for example, blood, interstitialfluid, cerebral spinal fluid, lymph fluid or urine) that can beanalyzed. Analytes can include naturally occurring substances,artificial substances, metabolites, and/or reaction products. In someembodiments, the analyte for measurement by the sensor heads, devices,and methods is analyte. However, other analytes are contemplated aswell, including but not limited to acarboxyprothrombin; acylcarnitine;adenine phosphoribosyl transferase; adenosine deaminase; albumin;alpha-fetoprotein; amino acid profiles (arginine (Krebs cycle),histidine/urocanic acid, homocysteine, phenylalanine/tyrosine,tryptophan); andrenostenedione; antipyrine; arabinitol enantiomers;arginase; benzoylecgonine (cocaine); biotinidase; biopterin; c-reactiveprotein; carnitine; carnosinase; CD4; ceruloplasmin; chenodeoxycholicacid; chloroquine; cholesterol; cholinesterase; conjugated 1-βhydroxy-cholic acid; cortisol; creatine kinase; creatine kinase MMisoenzyme; cyclosporin A; d-penicillamine; de-ethylchloroquine;dehydroepiandrosterone sulfate; DNA (acetylator polymorphism, alcoholdehydrogenase, alpha 1-antitrypsin, cystic fibrosis, Duchenne/Beckermuscular dystrophy, analyte-6-phosphate dehydrogenase, hemoglobin A,hemoglobin S, hemoglobin C, hemoglobin D, hemoglobin E, hemoglobin F,D-Punjab, beta-thalassemia, hepatitis B virus, HCMV, HIV-1, HTLV-1,Leber hereditary optic neuropathy, MCAD, RNA, PKU, Plasmodium vivax,sexual differentiation, 21-deoxycortisol); desbutylhalofantrine;dihydropteridine reductase; diptheria/tetanus antitoxin; erythrocytearginase; erythrocyte protoporphyrin; esterase D; fattyacids/acylglycines; free β-human chorionic gonadotropin; freeerythrocyte porphyrin; free thyroxine (FT4); free tri-iodothyronine(FT3); fumarylacetoacetase; galactose/gal-1-phosphate;galactose-1-phosphate uridyltransferase; gentamicin; analyte-6-phosphatedehydrogenase; glutathione; glutathione perioxidase; glycocholic acid;glycosylated hemoglobin; halofantrine; hemoglobin variants;hexosaminidase A; human erythrocyte carbonic anhydrase I;17-alpha-hydroxyprogesterone; hypoxanthine phosphoribosyl transferase;immunoreactive trypsin; lactate; lead; lipoproteins ((a), B/A-1, β);lysozyme; mefloquine; netilmicin; phenobarbitone; phenytoin;phytanic/pristanic acid; progesterone; prolactin; prolidase; purinenucleoside phosphorylase; quinine; reverse tri-iodothyronine (rT3);selenium; serum pancreatic lipase; sissomicin; somatomedin C; specificantibodies (adenovirus, anti-nuclear antibody, anti-zeta antibody,arbovirus, Aujeszky's disease virus, dengue virus, Dracunculusmedinensis, Echinococcus granulosus, Entamoeba histolytica, enterovirus,Giardia duodenalisa, Helicobacter pylori, hepatitis B virus, herpesvirus, HIV-1, IgE (atopic disease), influenza virus, Leishmaniadonovani, leptospira, measles/mumps/rubella, Mycobacterium leprae,Mycoplasma pneumoniae, Myoglobin, Onchocerca volvulus, parainfluenzavirus, Plasmodium falciparum, poliovirus, Pseudomonas aeruginosa,respiratory syncytial virus, rickettsia (scrub typhus), Schistosomamansoni, Toxoplasma gondii, Trepenoma pallidium, Trypanosomacruzi/rangeli, vesicular stomatis virus, Wuchereria bancrofti, yellowfever virus); specific antigens (hepatitis B virus, HIV-1);succinylacetone; sulfadoxine; theophylline; thyrotropin (TSH); thyroxine(T4); thyroxine-binding globulin; trace elements; transferring;UDP-galactose-4-epimerase; urea; uroporphyrinogen I synthase; vitamin A;white blood cells; and zinc protoporphyrin. Salts, sugar, protein, fat,vitamins, and hormones naturally occurring in blood or interstitialfluids can also constitute analytes in certain embodiments. The analytecan be naturally present in the biological fluid, for example, ametabolic product, a hormone, an antigen, an antibody, and the like.Alternatively, the analyte can be introduced into the body, for example,a contrast agent for imaging, a radioisotope, a chemical agent, afluorocarbon-based synthetic blood, or a drug or pharmaceuticalcomposition, including but not limited to insulin; ethanol; cannabis(marijuana, tetrahydrocannabinol, hashish); inhalants (nitrous oxide,amyl nitrite, butyl nitrite, chlorohydrocarbons, hydrocarbons); cocaine(crack cocaine); stimulants (amphetamines, methamphetamines, Ritalin,Cylert, Preludin, Didrex, PreState, Voranil, Sandrex, Plegine);depressants (barbituates, methaqualone, tranquilizers such as Valium,Librium, Miltown, Serax, Equanil, Tranxene); hallucinogens(phencyclidine, lysergic acid, mescaline, peyote, psilocybin); narcotics(heroin, codeine, morphine, opium, meperidine, Percocet, Percodan,Tussionex, Fentanyl, Darvon, Talwin, Lomotil); designer drugs (analogsof fentanyl, meperidine, amphetamines, methamphetamines, andphencyclidine, for example, Ecstasy); anabolic steroids; and nicotine.The metabolic products of drugs and pharmaceutical compositions are alsocontemplated analytes. Analytes such as neurochemicals and otherchemicals generated within the body can also be analyzed, such as, forexample, ascorbic acid, uric acid, dopamine, noradrenaline,3-methoxytyramine (3MT), 3,4-Dihydroxyphenylacetic acid (DOPAC),Homovanillic acid (HVA), 5-Hydroxytryptamine (5HT), and5-Hydroxyindoleacetic acid (FHIAA).

The term “A/D Converter” as used herein is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to hardware and/orsoftware that converts analog electrical signals into correspondingdigital signals.

The terms “processor module,” “microprocessor” and “processor” as usedherein are broad terms and are to be given their ordinary and customarymeaning to a person of ordinary skill in the art (and are not to belimited to a special or customized meaning), and furthermore referwithout limitation to a computer system, state machine, and the likethat performs arithmetic and logic operations using logic circuitry thatresponds to and processes the basic instructions that drive a computer.

The terms “sensor data”, as used herein is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and are not to be limited to a special or customizedmeaning), and furthermore refers without limitation to any dataassociated with a sensor, such as a continuous analyte sensor. Sensordata includes a raw data stream, or simply data stream, of analog ordigital signal directly related to a measured analyte from an analytesensor (or other signal received from another sensor), as well ascalibrated and/or filtered raw data. In one example, the sensor datacomprises digital data in “counts” converted by an A/D converter from ananalog signal (e.g., voltage or amps) and includes one or more datapoints representative of a glucose concentration. Thus, the terms“sensor data point” and “data point” refer generally to a digitalrepresentation of sensor data at a particular time. The term broadlyencompasses a plurality of time spaced data points from a sensor, suchas a from a substantially continuous glucose sensor, which comprisesindividual measurements taken at time intervals ranging from fractionsof a second up to, e.g., 1, 2, or 5 minutes or longer. In anotherexample, the sensor data includes an integrated digital valuerepresentative of one or more data points averaged over a time period.Sensor data may include calibrated data, smoothed data, filtered data,transformed data, and/or any other data associated with a sensor.

The term “calibration” as used herein is a broad term and is to be givenits ordinary and customary meaning to a person of ordinary skill in theart (and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to a process of determining arelationship between a raw data stream and corresponding reference data,which can be used to convert raw data into calibrated data (definedbelow). In some embodiments, such as continuous analyte sensors, forexample, calibration can be updated or recalibrated over time as changesin the relationship between the raw data and reference data occur, forexample, due to changes in sensitivity, baseline, transport, metabolism,and the like.

The terms “calibrated data” and “calibrated data stream” as used hereinare broad terms and are to be given their ordinary and customary meaningto a person of ordinary skill in the art (and are not to be limited to aspecial or customized meaning), and furthermore refer without limitationto data that has been transformed from its raw state to another stateusing a function, for example a conversion function, to provide ameaningful value to a user.

The terms “smoothed data” and “filtered data” as used herein are broadterms and are to be given their ordinary and customary meaning to aperson of ordinary skill in the art (and are not to be limited to aspecial or customized meaning), and furthermore refer without limitationto data that has been modified to make it smoother and more continuousand/or to remove or diminish outlying points, for example, by performinga moving average of the raw data stream. Examples of data filtersinclude FIR (finite impulse response), IIR (infinite impulse response),moving average filters, and the like.

The terms “smoothing” and “filtering” as used herein are broad terms andare to be given their ordinary and customary meaning to a person ofordinary skill in the art (and are not to be limited to a special orcustomized meaning), and furthermore refer without limitation to amathematical computation that attenuates or normalizes components of asignal, such as reducing noise errors in a raw data stream. In someembodiments, smoothing refers to modification of a data stream to makeit smoother and more continuous or to remove or diminish outlying datapoints, for example, by performing a moving average of the raw datastream.

The term “noise signal” as used herein is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to a signalassociated with noise on the data stream (e.g., non-analyte relatedsignal). The noise signal can be determined by filtering and/oraveraging, for example. In some embodiments, the noise signal is asignal residual, delta residual (difference of residual), absolute deltaresidual, and/or the like, which are described in more detail elsewhereherein.

The term “algorithm” as used herein is a broad term and is to be givenits ordinary and customary meaning to a person of ordinary skill in theart (and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to a computational process(associated with computer programming or other written instructions)involved in transforming information from one state to another.

The term “matched data pairs” as used herein is a broad term and is tobe given its ordinary and customary meaning to a person of ordinaryskill in the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to reference data(for example, one or more reference analyte data points) matched withsubstantially time corresponding sensor data (for example, one or moresensor data points).

The term “counts” as used herein is a broad term and is to be given itsordinary and customary meaning to a person of ordinary skill in the art(and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to a unit of measurement of adigital signal. In one example, a raw data stream measured in counts isdirectly related to a voltage (e.g., converted by an A/D converter),which is directly related to current from the working electrode. Inanother example, counter electrode voltage measured in counts isdirectly related to a voltage.

The term “sensor” as used herein is a broad term and is to be given itsordinary and customary meaning to a person of ordinary skill in the art(and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to any device (or portion of adevice) that measures a physical quantity and converts it into a signalthat can be processed by analog and/or digital circuitry. Thus, theoutput of a sensor may be an analog and/or digital signal. Examples ofsensors include analyte sensors, glucose sensors, temperature sensors,altitude sensors, accelerometers, and heart rate sensors.

The terms “glucose sensor” as used herein is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and are not to be limited to a special or customizedmeaning), and furthermore refer without limitation to any sensor bywhich glucose can be quantified (e.g., enzymatic or non-enzymatic). Forexample, some embodiments of a glucose sensor may utilize a membranethat contains glucose oxidase that catalyzes the conversion of oxygenand glucose to hydrogen peroxide and gluconate, as illustrated by thefollowing chemical reaction:

Glucose+O₂→Gluconate+H₂O₂

Because for each glucose molecule metabolized, there is a proportionalchange in the co-reactant O₂ and the product H₂O₂, one can use anelectrode to monitor the current change in either the co-reactant or theproduct to determine glucose concentration.

The terms “coupled”, “operably connected” and “operably linked” as usedherein are broad terms and are to be given their ordinary and customarymeaning to a person of ordinary skill in the art (and are not to belimited to a special or customized meaning), and furthermore referwithout limitation to one or more components being linked to anothercomponent(s), either directly or indirectly, in a manner that allowstransmission of signals between the components. For example, modules ofa computing device that communicate via a common data bus are coupled toone another. As another example, one or more electrodes of a glucosesensor can be used to detect the amount of glucose in a sample andconvert that information into a signal, e.g., an electrical orelectromagnetic signal; the signal can then be transmitted to anelectronic circuit. In this case, the electrode is “operably linked” tothe electronic circuitry, even though the analog signal from theelectrode is transmitted and/or transformed by analog and/or digitalcircuitry before reaching the electronic circuit. These terms are broadenough to include wireless connectivity.

The term “physically connected” as used herein is a broad term and is tobe given its ordinary and customary meaning to a person of ordinaryskill in the art (and are not to be limited to a special or customizedmeaning), and furthermore refers without limitation to one or morecomponents that are connected to another component(s) through directcontact and/or a wired connection, including connecting via one or moreintermediate physically connecting component(s). For example, a glucosesensor may be physically connected to a sensor electronics module, andthus the processor module located therein, either directly or via one ormore electrical connections.

The term “substantially” as used herein is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to being largely butnot necessarily wholly that which is specified.

The term “host” as used herein is a broad term and is to be given itsordinary and customary meaning to a person of ordinary skill in the art(and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to mammal, such as a humanimplanted with a device.

The term “continuous analyte sensor” as used herein is a broad term andis to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation to adevice, or portion of a device, that continuously or continuallymeasures a concentration of an analyte, for example, at time intervalsranging from fractions of a second up to, for example, 1, 2, or 5minutes, or longer. In one exemplary embodiment, a glucose sensorcomprises a continuous analyte sensor, such as is described in U.S. Pat.No. 7,310,544, which is incorporated herein by reference in itsentirety.

The term “continuous analyte sensing” as used herein is a broad term andis to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation to theperiod in which monitoring of an analyte is continuously or continuallyperformed, for example, at time intervals ranging from fractions of asecond up to, for example, 1, 2, or 5 minutes, or longer. In oneembodiment, a glucose sensor performs continuous analyte sensing inorder to monitor a glucose level in a corresponding host.

The terms “reference analyte monitor,” “reference analyte meter,” and“reference analyte sensor” as used herein are broad terms and are to begiven their ordinary and customary meaning to a person of ordinary skillin the art (and are not to be limited to a special or customizedmeaning), and furthermore refer without limitation to a device thatmeasures a concentration of an analyte and can be used as a referencefor a continuous analyte sensor, for example a self-monitoring bloodglucose meter (SMBG) can be used as a reference for a continuous glucosesensor for comparison, calibration, and the like.

The term “clinical acceptability”, as used herein, is a broad term andis to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and refers without limitation to determination ofthe risk of inaccuracies to a patient. Clinical acceptability mayconsider a deviation between time corresponding glucose measurements(e.g., data from a glucose sensor and data from a reference glucosemonitor) and the risk (e.g., to the decision making of a diabeticpatient) associated with that deviation based on the glucose valueindicated by the sensor and/or reference data. One example of clinicalacceptability may be 85% of a given set of measured analyte valueswithin the “A” and “B” region of a standard Clarke Error Grid when thesensor measurements are compared to a standard reference measurement.

The term “quality of calibration” as used herein, is a broad term and isto be given its ordinary and customary meaning to a person of ordinaryskill in the art (and is not to be limited to a special or customizedmeaning), and refers without limitation to the statistical associationof matched data pairs in the calibration set used to create theconversion function. For example, an R-value may be calculated for acalibration set to determine its statistical data association, whereinan R-value greater than 0.79 determines a statistically acceptablecalibration quality, while an R-value less than 0.79 determinesstatistically unacceptable calibration quality.

The term “sensor session” as used herein, is a broad term and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and is not to be limited to a special or customizedmeaning), and refers without limitation to a period of time a sensor isin use, such as but not limited to a period of time starting at the timethe sensor is implanted (e.g., by the host) to removal of the sensor(e.g., removal of the sensor from the host's body and/or removal of thesensor electronics module from the sensor housing).

The terms “noise,” “noise event(s),” “noise episode(s),” “signalartifact(s),” “signal artifact event(s),” and “signal artifactepisode(s)” as used herein are broad terms and are to be given theirordinary and customary meaning to a person of ordinary skill in the art(and are not to be limited to a special or customized meaning), andfurthermore refer without limitation to signal noise that issubstantially non-glucose related, such as interfering species, macro-or micro-motion, ischemia, pH changes, temperature changes, pressure,stress, or even unknown sources of mechanical, electrical and/orbiochemical noise for example.

The term “measured analyte values” as used herein is a broad term and isto be given its ordinary and customary meaning to a person of ordinaryskill in the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to an analyte valueor set of analyte values for a time period for which analyte data hasbeen measured by an analyte sensor. The term is broad enough to includesensor data from the analyte sensor before or after data processing inthe sensor and/or receiver (for example, data smoothing, calibration,and the like).

The term “estimated analyte values” as used herein is a broad term andis to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation to ananalyte value or set of analyte values, which have been algorithmicallyextrapolated from measured analyte values. In some embodiments,estimated analyte values are estimated for a time period during which nodata exists. However, estimated analyte values can also be estimatedduring a time period for which measured data exists, but is to bereplaced by algorithmically extrapolated (e.g. processed or filtered)data due to noise or a time lag in the measured data, for example.

The term “calibration information” as used herein is a broad term and isto be given its ordinary and customary meaning to a person of ordinaryskill in the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to any informationuseful in calibration of a sensor. Calibration information may includereference data received from a reference analyte monitor, including oneor more reference data points, one or more matched data pairs formed bymatching reference data (e.g., one or more reference glucose datapoints) with substantially time corresponding sensor data (e.g., one ormore continuous sensor data points), a calibration set formed from a setof one or more matched data pairs, a calibration line drawn from thecalibration set, in vitro parameters (e.g., sensor sensitivity), and/ora manufacturing code, for example.

The term “alarm” as used herein is a broad term, and is to be given itsordinary and customary meaning to a person of ordinary skill in the art(and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to an alert or signal, such as anaudible, visual, or tactile signal, triggered in response to one or morealarm conditions. In one embodiment, hyperglycemic and hypoglycemicalarms are triggered when present or predicted clinical danger isassessed based on continuous analyte data.

The term “transformed sensor data” as used herein is a broad term, andis to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation to anydata that is derived, either fully or in part, from raw sensor data fromone or more sensors. For example, raw sensor data over a time period(e.g., 5 minutes) may be processed in order to generated transformedsensor data including one or more trend indicators (e.g., a 5 minutetrend). Other examples of transformed data include filtered sensor data(e.g., one or more filtered analyte concentration values), calibratedsensor data (e.g., one or more calibrated analyte concentration values),rate of change information, trend information, rate of accelerationinformation, sensor diagnostic information, location information,alarm/alert information, calibration information, and/or the like.

The term “sensor information” as used herein is a broad term, and is tobe given its ordinary and customary meaning to a person of ordinaryskill in the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to informationassociated with measurement, signal processing (including calibration),alarms, data transmission, and/or display associated with a sensor, suchas a continuous analyte sensor. The term is broad enough to include rawsensor data (one or more raw analyte concentration values), as well astransformed sensor data. In some embodiments, sensor informationincludes displayable sensor information.

The term “displayable sensor information” as used herein is a broadterm, and is to be given its ordinary and customary meaning to a personof ordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation toinformation that is transmitted for display on one or more displaydevices. As is discussed elsewhere herein, the content of displayablesensor information that is transmitted to a particular display devicemay be customized for the particular display device. Additionally,formatting of displayable sensor information may be customized forrespective display devices. Displayable sensor information may includeany sensor data, including raw sensor data, transformed sensor data,and/or any information associated with measurement, signal processing(including calibration), and/or alerts associated with one or moresensors.

The term “data package” as used herein is a broad term, and is to begiven its ordinary and customary meaning to a person of ordinary skillin the art (and is not to be limited to a special or customizedmeaning), and furthermore refers without limitation to a combination ofdata that is transmitted to one or more display devices, such as inresponse to triggering of an alert. A data package may includedisplayable sensor information (e.g., that has been selected andformatted for a particular display device) as well as headerinformation, such as data indicating a delivery address, communicationprotocol, etc. Depending on the embodiment, a data package may comprisesmultiple packets of data that are separately transmitted to a displaydevice (and reassembled at the display device) or a single block of datathat is transmitted to the display device. Data packages may beformatted for transmission via any suitable communication protocol,including radio frequency, Bluetooth, universal serial bus, any of thewireless local area network (WLAN) communication standards, includingthe IEEE 802.11, 802.15, 802.20, 802.22 and other 802 communicationprotocols, and/or a proprietary communication protocol.

The term “direct wireless communication” as used herein is a broad term,and is to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation to a datatransmission that goes from one device to another device without anyintermediate data processing (e.g., data manipulation). For example,direct wireless communication between a sensor electronics module and adisplay device occurs when the sensor information transmitted from thesensor electronics module is received by the display device withoutintermediate processing of the sensor information. The term is broadenough to include wireless communication that is transmitted through arouter, a repeater, a telemetry receiver (e.g., configured tore-transmit the sensor information without additional algorithmicprocessing), and the like. The term is also broad enough to includetransformation of data format (e.g., via a Bluetooth receiver) withoutsubstantive transformation of the sensor information itself.

The term “prospective algorithm(s)” as used herein is a broad term, andis to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation toalgorithms that process sensor information in real-time (e.g.,continuously and/or periodically as sensor data is received from thecontinuous analyte sensor) and provide real-time data output (e.g.,continuously and/or periodically as sensor data is processed in thesensor electronics module).

The term “retrospective algorithm(s)” as used herein is a broad term,and is to be given its ordinary and customary meaning to a person ofordinary skill in the art (and is not to be limited to a special orcustomized meaning), and furthermore refers without limitation toalgorithms that process sensor information in retrospect, (e.g.,analysis of a set of data for a time period previous to the present timeperiod).

As employed herein, the following abbreviations apply: Eq and Eqs(equivalents); mEq (milliequivalents); M (molar); mM (millimolar) μM(micromolar); N (Normal); mol (moles); mmol (millimoles); μmol(micromoles); nmol (nanomoles); g (grams); mg (milligrams); μg(micrograms); Kg (kilograms); L (liters); mL (milliliters); dL(deciliters); μL (microliters); cm (centimeters); mm (millimeters); μm(micrometers); nm (nanometers); h and hr (hours); min. (minutes); s andsec. (seconds); ° C. (degrees Centigrade).

Overview

In some embodiments, a system is provided for continuous measurement ofan analyte in a host that includes: a continuous analyte sensorconfigured to continuously measure a concentration of the analyte in thehost and a sensor electronics module physically connected to thecontinuous analyte sensor during sensor use. In one embodiment, thesensor electronics module includes electronics configured to process adata stream associated with an analyte concentration measured by thecontinuous analyte sensor in order to generate sensor information thatincludes raw sensor data, transformed sensor data, and/or any othersensor data, for example. The sensor electronics module may further beconfigured to generate sensor information that is customized forrespective display devices, such that different display devices mayreceive different sensor information.

Alerts

In one embodiment, one or more alerts are associated with a sensorelectronics module. For example, each alert may include one or morealert conditions that indicate when the respective alert has beentriggered. For example, a hypoglycemic alert may include alertconditions indicating a minimum glucose level. The alert conditions mayalso be based on transformed sensor data, such as trending data, and/orsensor data from multiple different sensors (e.g. an alert may be basedon sensor data from both a glucose sensor and a temperature sensor). Forexample, a hypoglycemic alert may include alert conditions indicating aminimum required trend in the host's glucose level that must be presentbefore triggering the alert. The term “trend,” as used herein refersgenerally to data indicating some attribute of data that is acquiredover time, e.g., such as calibrated or filtered data from a continuousglucose sensor. A trend may indicate amplitude, rate of change,acceleration, direction, etc., of data, such as sensor data, includingtransformed or raw sensor data.

In one embodiment, each of the alerts is associated with one or moreactions that are to be performed in response to triggering of the alert.Alert actions may include, for example, activating an alarm, such asdisplaying information on a display of the sensor electronics module oractivating an audible or vibratory alarm coupled to the sensorelectronics module, and/or transmitting data to one or more displaydevices external to the sensor electronics module. For any deliveryaction that is associated with a triggered alert, one or more deliveryoptions define the content and/or format of the data to be transmitted,the device to which the data is to be transmitted, when the data is tobe transmitted, and/or a communication protocol for delivery of thedata.

In one embodiment, multiple delivery actions (each having respectivedelivery options) may be associated with a single alert such thatdisplayable sensor information having different content and formatting,for example, is transmitted to respective display devices in response totriggering of a single alert. For example, a mobile telephone mayreceive a data package including minimal displayable sensor information(that may be formatted specifically for display on the mobiletelephone), while a desktop computer may receive a data packageincluding most (or all) of the displayable sensor information that isgenerated by the sensor electronics module in response to triggering ofa common alert. Advantageously, the sensor electronics module is nottied to a single display device, rather it is configured to communicatewith a plurality of different display devices directly, systematically,simultaneously (e.g., via broadcasting), regularly, periodically,randomly, on-demand, in response to a query, based on alerts or alarms,and/or the like.

In some embodiments, clinical risk alerts are provided that includealert conditions that combine intelligent and dynamic estimativealgorithms that estimate present or predicted danger with greateraccuracy, more timeliness in pending danger, avoidance of false alarms,and less annoyance for the patient. In general, clinical risk alertsinclude dynamic and intelligent estimative algorithms based on analytevalue, rate of change, acceleration, clinical risk, statisticalprobabilities, known physiological constraints, and/or individualphysiological patterns, thereby providing more appropriate, clinicallysafe, and patient-friendly alarms. Co-pending U.S. Patent PublicationNo. 2007/0208246, which is incorporated herein by reference in itsentirety, describes some systems and methods associated with theclinical risk alerts (or alarms) described herein. In some embodiments,clinical risk alerts can be triggered for a predetermined time period toallow for the user to attend to his/her condition. Additionally, theclinical risk alerts can be de-activated when leaving a clinical riskzone so as not to annoy the patient by repeated clinical alarms (e.g.,visual, audible or vibratory), when the patient's condition isimproving. In some embodiments, dynamic and intelligent estimationdetermines a possibility of the patient avoiding clinical risk, based onthe analyte concentration, the rate of change, and other aspects of thedynamic and intelligent estimative algorithms. If there is minimal or nopossibility of avoiding the clinical risk, a clinical risk alert will betriggered. However, if there is a possibility of avoiding the clinicalrisk, the system is configured to wait a predetermined amount of timeand re-analyze the possibility of avoiding the clinical risk. In someembodiments, when there is a possibility of avoiding the clinical risk,the system is further configured to provide targets, therapyrecommendations, or other information that can aid the patient inproactively avoiding the clinical risk.

In some embodiments, the sensor electronics module is configured tosearch for one or more display devices within communication range of thesensor electronics module and to wirelessly communicate sensorinformation (e.g., a data package including displayable sensorinformation, one or more alarm conditions, and/or other alarminformation) thereto. Accordingly, the display device is configured todisplay at least some of the sensor information and/or alarm the host(and/or care taker), wherein the alarm mechanism is located on thedisplay device.

In some embodiments, the sensor electronics module is configured toprovide one or a plurality of different alarms via the sensorelectronics module and/or via transmission of a data packagingindicating an alarm should be initiated by one or a plurality of displaydevices (e.g., sequentially and/or simultaneously). In some embodiments,the sensor electronics module determines which of the one or more alarmsto trigger based on one or more alerts that are triggered. For example,when an alert triggers that indicates severe hypoglycemia, the sensorelectronics module can perform multiple actions, such as activating analarm on the sensor electronics module, transmitting a data package to asmall (key fob) indicating activation of an alarm on the display, andtransmitting a data package as a text message to a care provider. As anexample, a text message can appear on a small (key fob) display, cellphone, pager device, and/or the like, including displayable sensorinformation that indicates the host's condition (e.g., “severehypoglycemia”).

In some embodiments, the sensor electronics module is configured to waita time period for the host to respond to a triggered alert (e.g., bypressing or selecting a snooze and/or off function and/or button on thesensor electronics module and/or a display device), after whichadditional alerts are triggered (e.g., in an escalating manner) untilone or more alerts are responded to. In some embodiments, the sensorelectronics module is configured to send control signals (e.g., a stopsignal) to a medical device associated with an alarm condition (e.g.,hypoglycemia), such as an insulin pump, wherein the stop alert triggersa stop of insulin delivery via the pump.

In some embodiments, the sensor electronics module is configured todirectly, systematically, simultaneously (e.g., via broadcasting),regularly, periodically, randomly, on-demand, in response to a query(from the display device), based on alerts or alarms, and/or the liketransmit alarm information. In some embodiments, the system furtherincludes a repeater such that the wireless communication distance of thesensor electronics module can be increased, for example, to 10, 20, 30,50 75, 100, 150, or 200 meters or more, wherein the repeater isconfigured to repeat a wireless communication from the sensorelectronics module to the display device located remotely from thesensor electronics module. A repeater can be useful to families havingchildren with diabetes. For example, to allow a parent to carry, orplace in a stationary position, a display device, such as in a largehouse wherein the parents sleep at a distance from the child.

Display Devices

In some embodiments, the sensor electronics module is configured tosearch for and/or attempt wireless communication with a display devicefrom a list of display devices. In some embodiments, the sensorelectronics module is configured to search for and/or attempt wirelesscommunication with a list of display devices in a predetermined and/orprogrammable order (e.g., grading and/or escalating), for example,wherein a failed attempt at communication with and/or alarming with afirst display device triggers an attempt at communication with and/oralarming with a second display device, and so on. In one exemplaryembodiment, the sensor electronics module is configured to search forand attempt to alarm a host or care provider sequentially using a listof display devices, such as: 1) a default display device, 2) a key fobdevice, 3) a cell phone (via auditory and/or visual methods, such as,text message to the host and/or care provider, voice message to the hostand/or care provider, and/or 911).

Depending on the embodiment, one or more display devices that receivedata packages from the sensor electronics module are “dummy displays”,wherein they display the displayable sensor information received fromthe sensor electronics module without additional processing (e.g.,prospective algorithmic processing necessary for real-time display ofsensor information). In some embodiments, the displayable sensorinformation comprises transformed sensor data that does not requireprocessing by the display device prior to display of the displayablesensor information. Some display devices may comprise software includingdisplay instructions (software programming comprising instructionsconfigured to display the displayable sensor information and optionallyquery the sensor electronics module to obtain the displayable sensorinformation) configured to enable display of the displayable sensorinformation thereon. In some embodiments, the display device isprogrammed with the display instructions at the manufacturer and caninclude security and/or authentication to avoid plagiarism of thedisplay device. In some embodiments, a display device is configured todisplay the displayable sensor information via a downloadable program(for example, a downloadable Java Script via the internet), such thatany display device that supports downloading of a program (for example,any display device that supports Java applets) therefore can beconfigured to display displayable sensor information (e.g., mobilephones, PDAs, PCs and the like).

In some embodiments, certain display devices may be in direct wirelesscommunication with the sensor electronics module, however intermediatenetwork hardware, firmware, and/or software can be included within thedirect wireless communication. In some embodiments, a repeater (e.g., aBluetooth repeater) can be used to re-transmit the transmitteddisplayable sensor information to a location farther away than theimmediate range of the telemetry module of the sensor electronicsmodule, wherein the repeater enables direct wireless communication whensubstantive processing of the displayable sensor information does notoccur. In some embodiments, a receiver (e.g., Bluetooth receiver) can beused to re-transmit the transmitted displayable sensor information,possibly in a different format, such as in a text message onto a TVscreen, wherein the receiver enables direct wireless communication whensubstantive processing of the sensor information does not occur. In oneembodiment, the sensor electronics module directly wirelessly transmitsdisplayable sensor information to one or a plurality of display devices,such that the displayable sensor information transmitted from the sensorelectronics module is received by the display device withoutintermediate processing of the displayable sensor information.

In one embodiment, one or more display devices comprise built-inauthentication mechanisms, wherein authentication is required forcommunication between the sensor electronics module and the displaydevice. In some embodiments, to authenticate the data communicationbetween the sensor electronics module and display devices, achallenge-response protocol, such as a password authentication isprovided, where the challenge is a request for the password and thevalid response is the correct password, such that pairing of the sensorelectronics module with the display devices can be accomplished by theuser and/or manufacturer via the password. However, any knownauthentication system or method useful for telemetry devices can be usedwith the preferred embodiments.

In some embodiments, one or more display devices are configured to querythe sensor electronics module for displayable sensor information,wherein the display device acts as a master device requesting sensorinformation from the sensor electronics module (e.g., a slave device)on-demand, for example, in response to a query. In some embodiments, thesensor electronics module is configured for periodic, systematic,regular, and/or periodic transmission of sensor information to one ormore display devices (for example, every 1, 2, 5, or 10 minutes ormore). In some embodiments, the sensor electronics module is configuredto transmit data packages associated with a triggered alert (e.g.,triggered by one or more alert conditions). However, any combination ofthe above described statuses of data transmission can be implementedwith any combination of paired sensor electronics module and displaydevice(s). For example, one or more display devices can be configuredfor querying the sensor electronics module database and for receivingalarm information triggered by one or more alarm conditions being met.Additionally, the sensor electronics module can be configured forperiodic transmission of sensor information to one or more displaydevices (the same or different display devices as described in theprevious example), whereby a system can include display devices thatfunction differently with regard to how they obtain sensor information.

In some embodiments, as described in more detail elsewhere herein, adisplay device is configured to query the data storage memory in thesensor electronics module for certain types of data content, includingdirect queries into a database in the sensor electronics module's memoryand/or requests for configured or configurable packages of data contenttherefrom; namely, the data stored in the sensor electronics module isconfigurable, queryable, predetermined, and/or pre-packaged, based onthe display device with which the sensor electronics module iscommunicating. In some additional or alternative embodiments, the sensorelectronics module generates the displayable sensor information based onits knowledge of which display device is to receive a particulartransmission. Additionally, some display devices are capable ofobtaining calibration information and wirelessly transmitting thecalibration information to the sensor electronics module, such asthrough manual entry of the calibration information, automatic deliveryof the calibration information, and/or an integral reference analytemonitor incorporated into the display device. U.S. Patent PublicationNos. 2006/0222566, 2007/0203966, 2007/0208245, and 2005/0154271, all ofwhich are incorporated herein by reference in their entirety, describesystems and methods for providing an integral reference analyte monitorincorporated into a display device and/or other calibration methods thatcan be implemented with the preferred embodiments.

In general, a plurality of display devices (e.g., a small (key fob)display device, a larger (hand-held) display device, a mobile phone, areference analyte monitor, a drug delivery device, a medical device anda personal computer) are configured to wirelessly communicate with thesensor electronics module, wherein the one or more display devices areconfigured to display at least some of the displayable sensorinformation wirelessly communicated from the sensor electronics module,wherein displayable sensor information includes sensor data, such as rawdata and/or transformed sensor data, such as analyte concentrationvalues, rate of change information, trend information, alertinformation, sensor diagnostic information and/or calibrationinformation, for example.

Small (Key Fob) Display Device

In some embodiments, one the plurality of display devices is a small(e.g., key fob) display device 14 (FIG. 1) that is configured to displayat least some of the sensor information, such as an analyteconcentration value and a trend arrow. In general, a key fob device is asmall hardware device with a built-in authentication mechanism sized tofit on a key chain. However, any small display device 14 can beconfigured with the functionality as described herein with reference tothe key fob device 14, including a wrist band, a hang tag, a belt, anecklace, a pendent, a piece of jewelry, an adhesive patch, a pager, anidentification (ID) card, and the like, all of which are included by thephrase “small display device” and/or “key fob device” herein.

In general, the key fob device 14 includes electronics configured toreceive and display displayable sensor information (and optionallyconfigured to query the sensor electronics module for the displayablesensor information). In one embodiment, the electronics include a RAMand a program storage memory configured at least to display the sensordata received from the sensor electronics module. In some embodiments,the key fob device 14 includes an alarm configured to warn a host of atriggered alert (e.g., audio, visual and/or vibratory). In someembodiments, the key fob device 14 includes a user interface, such as anLCD 602 and one or more buttons 604 that allows a user to view data,such as a numeric value and/or an arrow, to toggle through one or morescreens, to select or define one or more user parameters, to respond to(e.g., silence, snooze, turn off) an alert, and/or the like.

In some embodiments, the key fob display device has a memory (e.g., suchas in a gig stick or thumb drive) that stores sensor, drug (e.g.,insulin) and other medical information, enabling a memory stick-typefunction that allows data transfer from the sensor electronics module toanother device (e.g., a PC) and/or as a data back-up location for thesensor electronics module memory (e.g., data storage memory). In someembodiments, the key fob display device is configured to beautomatically readable by a network system upon entry into a hospital orother medical complex.

In some embodiments, the key fob display device includes a physicalconnector, such as USB port 606, to enable connection to a port (e.g.,USB) on a computer, enabling the key fob to function as a data downloaddevice (e.g., from the sensor electronics module to a PC), a telemetryconnector (e.g., Bluetooth adapter/connector for a PC), and/or enablesconfigurable settings on the key fob device (e.g., via software on thePC that allows configurable parameters such as numbers, arrows, trend,alarms, font, etc.) In some embodiments, user parameters associated withthe small (key fob) display device can be programmed into (and/ormodified) by a display device such as a personal computer, personaldigital assistant, or the like. In one embodiment, user parametersinclude contact information, alert/alarms settings (e.g., thresholds,sounds, volume, and/or the like), calibration information, font size,display preferences, defaults (e.g., screens), and/or the like.Alternatively, the small (key fob) display device can be configured fordirect programming of user parameters. In some embodiments, wherein thesmall (key fob) display device comprises a telemetry module, such asBluetooth, and a USB connector (or the like), such that the small (keyfob) display device additionally functions as telemetry adapter (e.g.,Bluetooth adapter) enabling direct wireless communication between thesensor electronics module and the PC, for example, wherein the PC doesnot include the appropriate telemetry adapter therein.

Large (Hand-Held) Display Device

In some embodiments, one the plurality of display devices is a hand-helddisplay device 16 (FIG. 1) configured to display sensor informationincluding an analyte concentration and a graphical representation of theanalyte concentration over time. In general, the hand-held displaydevice comprises a display 608 sufficiently large to display a graphicalrepresentation 612 of the sensor data over a time period, such as aprevious 1, 3, 5, 6, 9, 12, 18, or 24-hours of sensor data. In someembodiments, the hand-held device 16 is configured to display a trendgraph or other graphical representation, a numeric value, an arrow,and/or to alarm the host. U.S. Patent Publication No. 2005/0203360,which is incorporated herein by reference in its entirety, describes andillustrates some examples of display of data on a hand-held displaydevice. Although FIG. 6 illustrates one embodiment of a hand-helddisplay device, the hand-held device can be any single applicationdevice or multi-application device, such as mobile phone, a palm-topcomputer, a PDA, portable media player (e.g., iPod, MP3 player), a bloodglucose meter, an insulin pump, and/or the like.

In some embodiments, a mobile phone (or PDA) is configured to display(as described above) and/or relay sensor information, such as via avoice or text message to the host and/or the host's care provider. Insome embodiments, the mobile phone further comprises an alarm configuredto warn a host of a triggered alert, such as in response to receiving adata package indicating triggering of the alert. Depending on theembodiment, the data package may include displayable sensor information,such as an on-screen message, text message, and/or pre-generatedgraphical representation of sensor data and/or transformed sensor data,as well as an indication of an alarm, such as an auditory alarm or avibratory alarm, that should be activated by the mobile phone.

In some embodiments, one of the display devices is a drug deliverydevice, such as an insulin pump and/or insulin pen, configured todisplay sensor information. In some embodiments, the sensor electronicsmodule is configured to wirelessly communicate sensor diagnosticinformation to the drug delivery device in order to enable to the drugdelivery device to consider (include in its calculations/algorithms) aquality, reliability and/or accuracy of sensor information for closedloop and/or semi-closed loop systems, which are described in more detailin U.S. Patent Publication No. 2005/0192557, which is incorporatedherein by reference in its entirety. In some alternative embodiments,the sensor electronic module is configured to wirelessly communicatewith a drug delivery device that does not include a display, forexample, in order to enable a closed loop and/or semi-closed loop systemas described above.

In some embodiments, one of the display devices is a drug deliverydevice is a reference analyte monitor, such as a blood glucose meter,configured to measure a reference analyte value associated with ananalyte concentration in a biological sample from the host.

Personal Computer Display Device

In some embodiments, one of the display devices is personal computer(PC) 20 (FIG. 1) configured to display sensor information. Preferably,the PC 24 has software installed, wherein the software enables displayand/or performs data analysis (retrospective processing) of the historicsensor information. In some embodiments, a hardware device can beprovided (not shown), wherein the hardware device (e.g., dongle/adapter)is configured to plug into a port on the PC to enable wirelesscommunication between the sensor electronics module and the PC. In someembodiments, the PC 24 is configured to set and/or modify configurableparameters of the sensor electronics module 12 and/or small (key fobdevice) 14, as described in more detail elsewhere herein.

Other Display Devices

In some embodiments, one of the display devices is an on-skin displaydevice that is splittable from, releasably attached to, and/or dockableto the sensor housing (mounting unit, sensor pod, or the like). In someembodiments, release of the on-skin display turns the sensor off; inother embodiments, the sensor housing comprises sufficient sensorelectronics to maintain sensor operation even when the on-skin displayis released from the sensor housing.

In some embodiments, one of the display devices is a secondary device,such as a heart rate monitor, a pedometer, a temperature sensor, a carinitialization device (e.g., configured to allow or disallow the car tostart and/or drive in response to at least some of the sensorinformation wirelessly communicated from the sensor electronics module(e.g., glucose value above a predetermined threshold)). In somealternative embodiments, one of the display devices is designed for analternative function device (e.g., a caller id device), wherein thesystem is configured to communicate with and/or translate displayablesensor information to a custom protocol of the alternative device suchthat displayable sensor information can be displayed on the alternativefunction device (display of caller id device).

Exemplary Configurations

FIG. 1 is a diagram illustrating one embodiment of a continuous analytesensor system 8 including a sensor electronics module 12. In theembodiment of FIG. 1, the system includes a continuous analyte sensor 10physically connected to a sensor electronics module 12, which is indirect wireless communication with a plurality of different displaydevices 14, 16, 18, and/or 20.

In one embodiment, the sensor electronics module 12 includes electroniccircuitry associated with measuring and processing the continuousanalyte sensor data, including prospective algorithms associated withprocessing and calibration of the sensor data. The sensor electronicsmodule 12 may be physically connected to the continuous analyte sensor10 and can be integral with (non-releasably attached to) or releasablyattachable to the continuous analyte sensor 10. The sensor electronicsmodule 12 may include hardware, firmware, and/or software that enablesmeasurement of levels of the analyte via a glucose sensor, such as ananalyte sensor. For example, the sensor electronics module 12 caninclude a potentiostat, a power source for providing power to thesensor, other components useful for signal processing and data storage,and a telemetry module for transmitting data from the sensor electronicsmodule to one or more display devices. Electronics can be affixed to aprinted circuit board (PCB), or the like, and can take a variety offorms. For example, the electronics can take the form of an integratedcircuit (IC), such as an Application-Specific Integrated Circuit (ASIC),a microcontroller, and/or a processor. The sensor electronics module 12includes sensor electronics that are configured to process sensorinformation, such as sensor data, and generate transformed sensor dataand displayable sensor information. Examples of systems and methods forprocessing sensor analyte data are described in more detail herein andin U.S. Pat. Nos. 7,310,544 and 6,931,327 and U.S. Patent PublicationNos. 2005/0043598, 2007/0032706, 2007/0016381, 2008/0033254,2005/0203360, 2005/0154271, 2005/0192557, 2006/0222566, 2007/0203966 and2007/0208245, all of which are incorporated herein by reference in theirentirety.

Referring again to FIG. 1, a plurality of display devices (14, 16, 18,and/or 20) are configured for displaying (and/or alarming) thedisplayable sensor information that has been transmitted by the sensorelectronics module 12 (e.g., in a customized data package that istransmitted to the display devices based on their respectivepreferences). For example, the display devices are configured to displaythe displayable sensor information as it is communicated from the sensorelectronics module (e.g., in a data package that is transmitted torespective display devices), without any additional prospectiveprocessing required for calibration and real-time display of the sensordata.

In the embodiment of FIG. 1, the plurality of display devices includes asmall (key fob) display device 14, such as a wrist watch, a belt, anecklace, a pendent, a piece of jewelry, an adhesive patch, a pager, akey fob, a plastic card (e.g., credit card), an identification (ID)card, and/or the like, wherein the small display device comprises arelatively small display (e.g., smaller than the large display device)and is configured to display certain types of displayable sensorinformation (e.g., a numerical value and an arrow, in some embodiments).In some embodiments, one of the plurality of display devices is a large(hand-held) display device 16, such as a hand-held receiver device, apalm-top computer and/or the like, wherein the large display devicecomprises a relatively larger display (e.g., larger than the smalldisplay device) and is configured to display a graphical representationof the continuous sensor data (e.g., including current and historicdata). Other display devices can include other hand-held devices, suchas a cell phone or PDA 18, an insulin delivery device, a blood glucosemeter, and/or a desktop or laptop computer 24.

Because different display devices provide different user interfaces,content of the data packages (e.g., amount, format, and/or type of datato be displayed, alarms, and the like) can be customized (e.g.,programmed differently by the manufacture and/or by an end user) foreach particular display device. Accordingly, in the embodiment of FIG.1, a plurality of different display devices are in direct wirelesscommunication with the sensor electronics module (e.g., such as anon-skin sensor electronics module 12 that is physically connected to thecontinuous analyte sensor 10) during a sensor session to enable aplurality of different types and/or levels of display and/orfunctionality associated with the displayable sensor information, whichis described in more detail elsewhere herein.

Continuous Sensor

In some embodiments, a glucose sensor comprises a continuous sensor, forexample a subcutaneous, transdermal (e.g., transcutaneous), orintravascular device. In some embodiments, the device can analyze aplurality of intermittent blood samples. The glucose sensor can use anymethod of glucose-measurement, including enzymatic, chemical, physical,electrochemical, spectrophotometric, polarimetric, calorimetric,iontophoretic, radiometric, immunochemical, and the like.

A glucose sensor can use any known method, including invasive, minimallyinvasive, and non-invasive sensing techniques (e.g., fluorescentmonitoring), to provide a data stream indicative of the concentration ofglucose in a host. The data stream is typically a raw data signal, whichis converted into a calibrated and/or filtered data stream that is usedto provide a useful value of glucose to a user, such as a patient or acaretaker (e.g., a parent, a relative, a guardian, a teacher, a doctor,a nurse, or any other individual that has an interest in the wellbeingof the host).

A glucose sensor can be any device capable of measuring theconcentration of glucose. One exemplary embodiment is described below,which utilizes an implantable glucose sensor. However, it should beunderstood that the devices and methods described herein can be appliedto any device capable of detecting a concentration of glucose andproviding an output signal that represents the concentration of glucose.

In one embodiment, the analyte sensor is an implantable glucose sensor,such as described with reference to U.S. Pat. No. 6,001,067 and U.S.Patent Publication No. US-2005-0027463-A1. In another embodiment, theanalyte sensor is a transcutaneous glucose sensor, such as describedwith reference to U.S. Patent Publication No. US-2006-0020187-A1. Instill other embodiments, the sensor is configured to be implanted in ahost vessel or extracorporeally, such as is described in U.S. PatentPublication No. US-2007-0027385-A1, co-pending U.S. Patent PublicationNo. US-2008-0119703-A1 filed Oct. 4, 2006, co-pending U.S. PatentPublication No. US-2008-0108942-A1 filed on Mar. 26, 2007, andco-pending U.S. Patent Application No. US-2007-0197890-A1 filed on Feb.14, 2007. In one alternative embodiment, the continuous glucose sensorcomprises a transcutaneous sensor such as described in U.S. Pat. No.6,565,509 to Say et al., for example. In another alternative embodiment,the continuous glucose sensor comprises a subcutaneous sensor such asdescribed with reference to U.S. Pat. No. 6,579,690 to Bonnecaze et al.or U.S. Pat. No. 6,484,046 to Say et al., for example. In anotheralternative embodiment, the continuous glucose sensor comprises arefillable subcutaneous sensor such as described with reference to U.S.Pat. No. 6,512,939 to Colvin et al., for example. In another alternativeembodiment, the continuous glucose sensor comprises an intravascularsensor such as described with reference to U.S. Pat. No. 6,477,395 toSchulman et al., for example. In another alternative embodiment, thecontinuous glucose sensor comprises an intravascular sensor such asdescribed with reference to U.S. Pat. No. 6,424,847 to Mastrototaro etal., for example.

FIGS. 2A and 2B are perspective and side views of a sensor systemincluding a mounting unit 214 and sensor electronics module 12 attachedthereto in one embodiment, shown in its functional position, including amounting unit and a sensor electronics module matingly engaged therein.In some embodiments, the mounting unit 214, also referred to as ahousing or sensor pod, comprises a base 234 adapted for fastening to ahost's skin. The base can be formed from a variety of hard or softmaterials, and can comprises a low profile for minimizing protrusion ofthe device from the host during use. In some embodiments, the base 234is formed at least partially from a flexible material, which is believedto provide numerous advantages over conventional transcutaneous sensors,which, unfortunately, can suffer from motion-related artifactsassociated with the host's movement when the host is using the device.The mounting unit 214 and/or sensor electronics module 12 can be locatedover the sensor insertion site to protect the site and/or provide aminimal footprint (utilization of surface area of the host's skin).

In some embodiments, a detachable connection between the mounting unit214 and sensor electronics module 12 is provided, which enables improvedmanufacturability, namely, the relatively inexpensive mounting unit 214can be disposed of when replacing the sensor system after its usablelife, while the relatively more expensive sensor electronics module 12can be reusable with multiple sensor systems. In some embodiments, thesensor electronics module 12 is configured with signal processing(programming), for example, configured to filter, calibrate and/or otheralgorithms useful for calibration and/or display of sensor information.However, an integral (non-detachable) sensor electronics module can beconfigured.

In some embodiments, the contacts 238 are mounted on or in a subassemblyhereinafter referred to as a contact subassembly 236 configured to fitwithin the base 234 of the mounting unit 214 and a hinge 248 that allowsthe contact subassembly 236 to pivot between a first position (forinsertion) and a second position (for use) relative to the mounting unit214. The term “hinge” as used herein is a broad term and is used in itsordinary sense, including, without limitation, to refer to any of avariety of pivoting, articulating, and/or hinging mechanisms, such as anadhesive hinge, a sliding joint, and the like; the term hinge does notnecessarily imply a fulcrum or fixed point about which the articulationoccurs. In some embodiments, the contacts 238 are formed from aconductive elastomeric material, such as a carbon black elastomer,through which the sensor 10 extends.

In certain embodiments, the mounting unit 214 is provided with anadhesive pad 208, disposed on the mounting unit's back surface andincludes a releasable backing layer. Thus, removing the backing layerand pressing the base portion 234 of the mounting unit onto the host'sskin adheres the mounting unit 214 to the host's skin. Additionally oralternatively, an adhesive pad can be placed over some or all of thesensor system after sensor insertion is complete to ensure adhesion, andoptionally to ensure an airtight seal or watertight seal around thewound exit-site (or sensor insertion site) (not shown). Appropriateadhesive pads can be chosen and designed to stretch, elongate, conformto, and/or aerate the region (e.g., host's skin). The embodimentsdescribed with reference to FIGS. 2A and 2B are described in more detailwith reference to U.S. Pat. No. 7,310,544, which is incorporated hereinby reference in its entirety. Configurations and arrangements canprovide water resistant, waterproof, and/or hermetically sealedproperties associated with the mounting unit/sensor electronics moduleembodiments described herein.

Various methods and devices that are suitable for use in conjunctionwith aspects of some embodiments are disclosed in U.S. PatentPublication No. US-2009-0240120-A1, which is incorporated herein byreference in its entirety.

Use of Data Communication Protocols

FIG. 3 is an exemplary block diagram illustrating various elements ofone embodiment of a continuous analyte sensor system 8 and displaydevice 14, 16, 18, 20. The sensor system 8 may include a sensor 312(also designated 10 in FIG. 1) coupled to a sensor measurement circuit310 for processing and managing sensor data. The sensor measurementcircuit 310 may be coupled to a processor 314 (part of item 12 in FIG.1). In some embodiments, the processor 314 may perform part or all ofthe functions of the sensor measurement circuit 310 for obtaining andprocessing sensor measurement values from the sensor 312. The processormay be further coupled to a transceiver 316 (part of item 12 in FIG. 1)for sending sensor data and receiving requests and commands from anexternal device, such as the display device 14, 16, 18, 20, which isused to display or otherwise provide the sensor data to a user. Thesensor system 8 may further include a memory 318 (part of item 12 inFIG. 1) and a real time clock 320 (part of item 12 in FIG. 1) forstoring and tracking sensor data.

Wireless communication protocols may be used to transmit and receivedata between the sensor system 8 and the display device 14, 16, 18, 20.The wireless protocol used may be designed for use in a wireless sensornetwork that is optimized for periodic and small data transmissions(that may be transmitted at low rates if necessary) to and from multipledevices in a close range (e.g., a personal area network (PAN)). Forexample, the protocol may be optimized for periodic data transfers wheretransceivers may be configured to transmit data for short intervals andthen enter low power modes for long intervals. The protocol may have lowoverhead requirements both for normal data transmissions and forinitially setting up communication channels (e.g., by reducing headeroverhead) to reduce power consumption. In some embodiments, burstbroadcasting schemes (e.g., one way communication) may be used. This mayeliminate overhead required for acknowledgement signals and allow forperiodic transmissions that consume little power.

The protocol may further be configured to establish communicationchannels with multiple devices while implementing interference avoidanceschemes. In some embodiments, the protocol may make use of adaptiveisochronous network topologies that define various time slots andfrequency bands for communication with several devices. The protocol maythus modify transmission windows and frequencies in response tointerference and to support communication with multiple devices.Accordingly, the wireless protocol may use time and frequency divisionmultiplexing (TDMA) based schemes. The wireless protocol may also employdirect sequence spread spectrum (DSSS) and frequency-hopping spreadspectrum schemes. Various network topologies may be used to support lowpower wireless communication such as peer-to-peer, start, tree, or meshnetwork topologies. The wireless protocol may operate in variousfrequency bands such as an open ISM band such as 2.4 GHz. Furthermore,to reduce power usage, the wireless protocol may adaptively configuredata rates according to power consumption.

The display device 14, 16, 18, 20 may be used for alerting and providingsensor information to a user, and may include a processor 330 forprocessing and managing sensor data. The display device 14, 16, 18, 20may include a display 332, a memory 334, and a real time clock 336 fordisplaying, storing and tracking sensor data respectively. The displaydevice 14, 16, 18, 20 may further include a transceiver 338 forreceiving sensor data and for sending requests, instructions, and datato the sensor system 8. The transceiver 338 may further employ acommunication protocol.

In some embodiments, when a standardized communication protocol is used,commercially available transceiver circuits may be utilized thatincorporate processing circuitry to handle low level data communicationfunctions such as the management of data encoding, transmissionfrequencies, handshake protocols, and the like. In these embodiments,the processor 314, 330 does not need to manage these activities, butrather provides desired data values for transmission, and manages highlevel functions such as power up or down, set a rate at which messagesare transmitted, and the like. Instructions and data values forperforming these high level functions can be provided to the transceivercircuits via a data bus and transfer protocol established by themanufacturer of the transceiver circuit 316.

Components of the analyte sensor system 8 may require replacementperiodically. For example, the analyte sensor system 8 may include animplantable sensor 312 that may be attached to a sensor electronicsmodule that includes the sensor measurement circuit 310, the processor314, memory 318, and transceiver 316, and battery (not shown). Thesensor 312 may require periodic replacement (e.g., every 7-30 days). Thesensor electronics module may be configured to be powered and active formuch longer than the sensor 312 (e.g., for six months or more) until thebattery needs replacement. Replacing these components may be difficultand require the assistance of trained personnel. Reducing the need toreplace such components, particularly the battery, significantlyimproves the convenience of the analyte sensor system 8 to the user. Insome embodiments, the sensor session as defined above may correspond tothe life of the sensor 312 (e.g., 7-30 days). When a sensor electronicmodule is used for the first time (or reactivated once a battery hasbeen replaced in some cases), it may be connected to a sensor 312 and asensor session may be established. As will be further described below,there may be a process for initially establishing communication betweena display device 14, 16, 18, 20 and the sensor electronics module whenit is first used or re-activated (e.g., the battery is replaced). Oncethe display device 14, 16, 18, 20 and sensor electronics module haveestablished communication, the display device 14, 16, 18, 20 and sensorelectronics module may periodically and/or continuously be incommunication over the life of several sensors 312 until, for example,the battery needs to be replaced. Each time a sensor 312 is replaced, anew sensor session may be established. The new sensor session may beinitiated through a process completed using a display device 14, 16, 18,20 and the process may be triggered by notifications of a new sensor viathe communication between the sensor electronics module and the displaydevice 14, 16, 18, 20 that may be persistent across sensor sessions.

The analyte sensor system 8 gathers analyte data from the sensor 312that it periodically sends to the display device 14, 16, 18, 20. Datapoints are gathered and transmitted over the life of the sensor (e.g.,1-30 days or more). New measurements may need to be transmitted oftenenough to adequately monitor glucose levels. Rather than having thetransmission and receiving circuitry of each of the sensor system 8 anddisplay device 12, 16, 18, continuously communicating, the analytesensor system 8 and display device 14, 16, 18, 20 may regularly andperiodically establish a communication channel between them. Thus,sensor system 8 can communicate via wireless transmission with displaydevice 14, 16, 18, 20 (e.g., a hand-held computing device) atpredetermined time intervals. The duration of the predetermined timeinterval can be selected to be long enough so that the sensor system 8does not consume too much power by transmitting data more frequentlythan needed, yet frequent enough to provide substantially real-timesensor information (e.g., measured glucose values) to the display device14, 16, 18, 20 for output (e.g., display) to a user. While thepredetermined time interval is every five minutes in one embodiment, itis appreciated that this time interval can be varied to be any desiredlength of time.

FIG. 4A is a flow diagram of an exemplary communication between ananalyte sensor system 8 and a display device 14, 16, 18, 20 forcommunicating glucose measurement values. The data transfer may happenperiodically, at times separated by an update interval T_(update) thatmay correspond to a period of obtaining and sending a recently measuredglucose value (e.g., five minutes). In between these data transferprocedures, the transceiver 316 of the analyte sensor system 8 can bepowered down or in a sleep mode to conserve battery life. As such, theanalyte sensor system 8 may therefore establish a communication channelwith the display device 14, 16, 18, 20 once per update intervalT_(update). Establishing a communication channel may occur during atransmission window T_(window) within an update interval T_(update).

To establish a communication channel, the analyte sensor system 8 maysend one or more message beacons during of a transmission windowT_(window) within an update interval T_(update). Each message beacon maybe considered an invitation for a display device 14, 16, 18, 20 toestablish a communication channel with the sensor system 8. A beacon mayinclude data including a challenge value for authenticating a displaydevice 14, 16, 18, 20 as will be further described below. During initialsystem set up, the display device 14, 16, 18, 20 may listen continuouslyuntil such a message beacon is received. When the beacon is successfullyreceived, the display device 14, 16, 18, 20 can acknowledge thereception to establish communication between the devices. As will befurther described below, in response to the beacon, the display device14, 16, 18, 20 may send a message requesting a measurement along with acomputed value for authentication. Once authenticated, the analytesensor system 8 and display device 14, 16, 18, 20 may exchangeinformation to determine how data will be exchanged (e.g., a specificfrequency, time slot assignment, etc.). When the desired datacommunication is complete, the channel can be closed, and thetransceiver 316 of the analyte sensor system 8 (and possibly thetransceiver 338 of the display device 14, 16, 18, 20 as well) can bepowered down. The entire data transmission window interval T_(window)for providing data to one or more display devices 14, 16, 18, 20 may bea small fraction of the update interval T_(update). For example,T_(update) may be five minutes and the data transmission window intervalT_(window) may be thirty seconds. As such, the transceiver 316 of theanalyte sensor system 8 may only be powered for substantially 30 secondsof a five minute T_(update) interval. This may significantly reducepower consumption. In some cases, the transceiver 316 is not completelypowered down, but enters a low-power mode when not transmitting. After aT_(update) interval has elapsed, the transceivers 316, 338 can besynchronized to power up again substantially simultaneously, andestablish a new communication channel using the same process to exchangeany new data as shown in FIG. 4A. This process may continue, with newcommunication channels being established at the predetermined intervals.

To allow for some loss of synchronization between the two devices inbetween transmissions, the analyte sensor system 8 may be configured tosend a series of message beacons 402 in a window of time around thescheduled transmission time (e.g., 8 message beacons per second for 4seconds). Any one of the message beacons can be used to initiate theestablishment of a new communication channel when it is received by thedisplay device 14, 16, 18, 20. After communicating with one deviceduring the transmission window, the analyte sensor system 8 may send outfurther message bacons 404. These beacons can be received and used toestablish other communication channels with other devices (e.g., otherdisplay devices) during the transmission window T_(window). However, insome embodiments, if it is known that the analyte sensor system 8 isonly communicating with a single display device, then the transmissionwindow T_(window) can be terminated at the same time as closing thecommunication channel with the display device.

FIG. 4B is a timing diagram of an exemplary sequence for establishing acommunication channel between an analyte sensor system 8 and a displaydevice 14, 16, 18, 20. The display device 14, 16, 18, 20 may initially“wake up” its transceiver 316 and wait to receive a beacon from theanalyte sensor system 8. Once the analyte sensor system 8 begins sendingbeacons, it may take one, two, or more beacons for the display device14, 16, 18, 20 to receive the beacon and respond with a request. Oncethe beacon is received and the request sent, data may thereafter be sentand/or received as shown by the shaded time slots. The channel can thenbe closed once analyte sensor system 8 and display device 14, 16, 18, 20determine that all requested data has been transmitted to the respectivedevices or it the transmission window time expires. At the start of anew T_(update) interval, the process is repeated.

Continuously re-establishing a new communication channel to allow forpartially or wholly powering down the transceiver 316 during each updateinterval T_(update) can provide significant power savings and can allowthe sensor electronics module 12 to operate continuously for six monthsor more without requiring a battery replacement. Furthermore, ratherthan blindly transmitting glucose data points during the transmissionwindow T_(window), communication channels may be established so thatonly the desired display devices 14, 16, 18, may receive the glucoseinformation. This may prevent unauthorized use and interception ofglucose measurement values. In addition, by establishing a securetwo-way communication channel, requests for specific glucose measurementvalues or communication of calibration or configuration information maybe transmitted on an as-needed/requested basis between the sensor system8 and display device 14, 16, 18, 20.

Also, in some embodiments, the communication window need not open duringevery update interval T_(update). Instead, the window can open everysecond, third or fourth update interval T_(update), for example, so thatcommunication between the sensor system 8 with the display device 14,16, 18, 20 occurs less frequently than every update interval T_(update).Doing so can further reduce power consumption. Accordingly, a windowfrequency variable F_(window) can be used that dictates a frequency thewindow opens.

In some embodiments, the update interval T_(update), transmission windowT_(window) and/or window frequency F_(window) may be variable.T_(update), T_(window) and/or F_(window) can be user configurable (e.g.,by inputting a value for the variable using user interface of displaydevice 14, 16, 18, 20) and/or automatically varied by the sensor system8 or display device 14, 16, 18, 20 based on one or more criteria. Thecriteria can include: (i) a monitored battery power of the sensor system8, (ii) a currently measured, previously measured and/or predictedglucose concentrations meeting or exceeding a predetermined threshold,(iii) a glucose concentration trend of the host based on currentlymeasured, previously measured and/or predicted glucose concentrations,(iv) a rate of change of glucose concentration of the host basedcurrently measured, previously measured and/or predicted glucoseconcentrations meeting or exceeding a predetermined threshold, (v)whether the host is determined to be in or near hyperglycemia based oncurrently measured, previously measured and/or predicted glucoseconcentrations, (vi) whether the host is determined to be in or nearhypoglycemia based on currently measured, previously measured and/orpredicted glucose concentrations, (vii) user inputted activity of thehost (e.g., exercising or sleeping), (viii) time since a sensor sessionhas started (e.g., when a new sensor 10 is used), (ix) one or moreerrors detected by sensor system 8 or display device 14, 16, 18, 20, and(x) type of display device.

T_(update), T_(window) and/or F_(window) and other configuration itemsdescribed herein may form part of a communication protocol profile thatmay be stored on any device that implements the fundamentalcommunication protocol to allow for a customized use of the protocol forreceiving glucose measurement values, such as sensor system 10 anddisplay device 14, 16, 18, 20.

FIG. 5 is a flowchart of an exemplary method for sending glucosemeasurement values from an analyte sensor system 8 to a display device14, 16, 18, 20. At a pre-determined time in an update intervalT_(update), an analyte sensor system 8 may activate a transceiver 316 asshown in block 502. This may include powering the transceiver 316 orawakening the transceiver 316 from a low power mode/state such as asleep mode. In block 504, the transceiver 316 may open and establish anauthenticated two-way communication channel between the analyte sensorsystem 8 and a display device 14, 16, 18, 20. If the channel isestablished, in block 506, the analyte sensor system 8 and the displaydevice 14, 16, 18, 20 may transmit information between them, eitherautomatically (e.g., device determines a triggering event to transmitspecific information) or in response to a request received from theother device. Such information can include one or more glucosemeasurement values, calibration information, alert settings,communication synchronization information, and the like. Once thetransmission is complete and data requested by the display device 14,16, 18, 20 and sensor system 10 is sent, the analyte sensor system 8 mayclose the communication channel. In block 510, the analyte sensor system8 may deactivate the transceiver 316 such as powering-down thetransceiver or causing it to go into a low power mode. The operations inblock 504 through 508 may be repeated with additional display devicesuntil the transmission window T_(window) closes. The analyte sensorsystem 8 may then wait for the next transmission window T_(window) toopen as shown in block 512, and in the meantime gather glucosemeasurement values, before the process is repeated continuously over theduration of a sensor session (e.g., corresponding to the life ofnon-durable sensor). Between each transmission window T_(window), a newanalyte sensor measurement may be obtained and stored for transmission.

Sensor Electronics Unit Window Transitioning

In some embodiments, the sensor electronics module 12 can be placed in amode wherein transmission windows occur more frequently than duringnormal use. This can be useful a new device is to be paired with thesensor electronics module, for example, to speed up pairing betweendevices.

In some implementations, when the sensor electronics module 12 is firstused, a display device with which a user wants to pair the sensorelectronics module does not have information about when the sensorelectronics module will next open a transmission window T-_(window).Further, the window frequency F_(window) may be low, such as a windowopening only every 5 minutes. As a consequence, a display device may notbe able to be paired with the sensor electronics module for nearly fiveminutes if the display device is constantly listening for beacons fromthe sensor electronics module. This can result in a long pairing processthat expends valuable power due.

Accordingly, in some implementations, the sensor electronics module 12can be switched (manually or automatically) from a first state to asecond state to facilitate pairing, wherein the window frequencyF_(window) is greater in the second state than in the first state. Afterparing, the sensor electronics module 12 can then switch back to thefirst state or switch to a third state that has a window frequency thatis different from the first state and the second state. The sensorelectronics module can switch back to the first state or to the thirdstate automatically in response to the sensor electronics moduledetermining a successful pairing between the two devices, or switchedback to the first state or to the third state manually by a user via anexternal switch or user input using an electronics user interface. Inone implementation, the first state corresponds to a storage mode inwhich window frequency F_(window) is 0 (i.e. transmission window is notentered to conserve power) and the third state corresponds to a normaloperational state in which window frequency F_(window) is greater thanzero, but less than the second state. As one non-limiting example,window frequency F_(window) during the second state can be 30 secondsand the window frequency F_(window) during the third state can be 5minutes.

The following is a non-limiting exemplary implementation to illustrateswitching the window frequency F_(window) for power savings and tofacilitate pairing. As discussed above, the sensor electronics module 12can be a separate unit that is configured to be connected to acontinuous analyte sensor 10 as discussed above and illustrated in FIGS.2A and 2B, for example. The sensor electronics module 12 can bemanufactured and then stored in a container, such as a box, prior touse. To conserve power, the sensor electronics module 12 can be placedin a low power state while in the container and thereafter switched topairing state after removal of the sensor electronics unit from thestorage container.

The sensor electronics module 12 can be kept in the low power statethrough use of an external magnet and a reed switch or hall-effectswitch within the sensor electronics module. Using an external magnet tokeep a sensor electronics module in a low power mode is described inmore detail in U.S. patent application Ser. No. 13/247,856 filed on Sep.28, 2011, the content of which are hereby incorporated by reference inits entirety. A magnet can be placed next to the sensor electronicsmodule 12 during manufacturing next to the sensor electronics module 12in the container to keep the sensor electronics module in the low powerstate while in the container. When it is desired to use the sensorelectronics module 12, the sensor electronics module 12 can be removedfrom the container and the magnet removed from the proximity of thesensor electronics module to cause the sensor electronics module toswitch to the pairing state. A reed switch, hall-effect switch or thelike can reside in the sensor electronics module to trigger theswitching of the sensor electronics module from the low power state tothe pairing state, for example.

Accordingly, the sensor electronics module 12 can be in the low powerstate while in storage, switched to the pairing state when removed fromstorage (e.g. by removing a magnet) and then switched to a normaloperational state once the sensor electronics module 12 is paired with adisplay device. The low power state can include keeping the transceiverpowered off or otherwise in a low power state wherein no beacons aretransmitted. The pairing state can include a high window frequencyF_(window), such as every 30 seconds, wherein one or more beacons aretransmitted during each window. The normal operational state can includea relatively low window frequency F_(window), such as every 5 minutes,for opening a communication channel with one or more display devices toexchange information, including sensor data values.

Further, in some implementations of the above-described beacon intervaltransition process, the sensor electronics module will automaticallychange from the high window frequency F_(window) used to facilitateparing (e.g., the second state) to the normal operational windowfrequency F_(window) (e.g., the third state) after a predeterminedamount of time, such as 1 hour, should a successful pairing not occurwithin that time. This way, valuable battery power is not wasted byhaving a high window frequency F_(window) for an extended period oftime.

Display Device Window Transitioning

In some embodiments, the display device 14, 16, 18, 20 is configuredthrough software instructions executed by a processor of the displaydevice to vary windows for listening for a beacon from sensorelectronics module 12. Doing so can conserve battery power as opposed toconstantly having the display device listen for a beacon from the sensorelectronics module.

In some implementations, a state based approach for RF windowing can beused. The following is an example of states and substates that can beused in an implementation, but it is understood that more or fewer ofthese states and substates can be used depending upon the particularneeds of a user. Further, it should be understood that, while thisexample provides times for the windowing, other times can be useddepending upon the particular needs of a user and device properties.This example also contemplates implementations wherein the displaydevice has a software application stored on the display device (whichmay be referred to herein as an “app”) that is configured to cause thedisplay device to request data from the sensor electronics module. Theapplication may run as a background process on the display device and,while it is run in the background, the display device does not listenfor beacons. States and substates in this example are the following:

-   -   1. RFWindowState. Search: When this state is entered, the        display device opens up the RF window for the same or slightly        greater period than the window frequency of the sensor        electronics unit during normal operation so at least one beacon        is to be received within this period. For example, if the        windowing frequency of the sensor electronics module is 5        minutes, the window in this state can be set to be open for 5        minutes and 5 seconds. This state is entered:        -   a. When the display device has been in RFWindowState.Idle            mode for 30 minutes; OR        -   b. When the display device is in RFWindowState.Idle and the            app is brought up from background.    -   2. RFWindowState.PairingSearch: This is very similar to        RFWindowState.Search and opens up the RF window for a slightly        longer period than the window frequency of the sensor        electronics unit during normal operation to ensure at least one        beacon cycle falls within this timeframe. The window can be open        for 5 minutes and 5 seconds, for example. This state is entered:        -   a. When the user enters a new transmitter id (as discussed            in more detail under the heading Transceiver Pairing            Authentication Scheme); OR        -   b. When the display device has been in            RFWindowState.PairingIdle mode for 30 minutes; OR        -   c. When the display device is in RFWindowState.PairingIdle            and the app is brought up from background    -   3. RFWindowState.Locked: This is a state when the display device        has received a beacon recently, and has a good estimate of when        to expect the next beacon. This includes situations where the        display device has missed receiving any beacons during less than        six consecutive previous beaconing windows (“beaconing cycles”)        from the sensor electronics module. This state has the following        sub-states:        -   a. RFWindowSubstateId.OpenWaitingForBeacon: This is entered            when the RF window is opened while in RFWindowState.Locked            state. This event is triggered by a timer in the display            device for waiting for the next beacon cycle to go off while            in RFWindowSubstateId.ClosedWaitingForNextBeacon sub-state.        -   b. RFWindowSubstateId.PageExchange: This is entered when a            beacon is received while in RFWindowState.Search,            RFWindowState.PairingSearch, or RFWindowState.Locked            (sub-state RFWindowSubstate.OpenWaitingForBeacon) states.        -   c. RFWindowSubstateId.ClosedWaitingForNextBeacon: This state            is entered when the display device has finished processing            all data packet exchanges for a current transmission window.    -   4. RFWindowState.Idle: This state is entered when:        -   a. The display device is in RFWindowState.Locked state, but            has missed 6 beacon cycles OR        -   b. The display device did not get any beacons in            RFWindowState.Search state for 5m5s.    -   The display device stays in RFWindowState.Idle for 30 minutes or        until the user activates the app, at which point RFWindowState.        Search state is entered.    -   5. RFWindowState.PairingIdle: This state is entered when:        -   a. The display device did not get any beacons in            RFWindowState.PairingSearch state for 5m5s    -   6. RFWindowState.Inactive: This is the state when the display        device does not have a transmitter id entered (i.e. it is zero).

Transceiver Pairing Authentication Scheme

In some embodiments, pairing of two devices (e.g., a master and slavedevice) may be required to establish a relationship between two devicesthat want to communicate with one another. Pairing may be accomplishedduring the channel establishment process described above between the twodevices. Establishing a channel may involve broadcasting a unique ID byone device and a search and acquisition of this ID by another device.

A parameter that may be used in device pairing is the master device ID.In order to establish a communication channel, a master transmitter maybroadcast its device ID (along with some other information) in the abovedescribed beacon and the receiver checks for the presence of the deviceID of the transmitter with which it wants to communicate in the receivedbeacons. The device ID may be a 2-byte value representing a specificmaster device, for example.

Although a master device ID may provide some level of security, in thata slave device can be programmed to communicate only with a masterdevice having a particular device ID number, additional security can beuseful in some embodiments. As described above, to save power bydeactivating the transceiver 316 of the analyte sensor system 8, acommunication channel may be re-established during each update intervalT_(update). As such, as part of the channel establishment process,regular and repeated re-authentication may also be provided.

To provide additional security, some embodiments of the presentinvention can use two pieces of information to pair a receiver with aparticular transceiver device. These two pieces of information includethe device ID described above and another value which is referred toherein as a sensor security code. The device ID is used as describedabove to filter receipt of non-matching messages at the lowest layer ofthe protocol stack. The sensor security code is used for a key basedauthentication scheme at the software application layer of the system.In some embodiments, both the device ID and the sensor security code canbe derived from an identifier (e.g., a manufacturer's serial number)associated with the sensor system 8 per the description below.

As seen in the embodiment of FIG. 1, the sensor system 8 comprises twofundamental components, the continuous sensor 10 and the electronicsmodule 12. These two components may be separable from one another,allowing, for example, replacement of the continuous sensor portion 10.In this case, the identifier may be etched into, printed on or otherwiseattached to a housing of the electronics module portion 12.

The sensor system 8 may include seven alphanumeric characters printed ona housing of the sensor system 8, which can comprise the identifier usedfor identification purposes. This alphanumeric series of characters maybe used to generate both the device ID used in the master beacons toestablish a channel and to generate the sensor security code used foradditional security in the glucose monitoring system. To maintain gooddata security, the alphanumeric characters and the sensor security codeneed not be transmitted over a wireless communication channel at anytime.

In some embodiments, the seven alphanumeric characters are converted toseven 5 bit binary values as shown for example in FIG. 6A. These 35 bitsare then concatenated together and divided into a device ID and sensorsecurity code as shown for example in FIG. 4B. The most significant 11bits, used for the device ID, are left-shifted by one bit and a one isinserted on the right, to produce a 12 bit value. Inserting the 1 on theright prevents the device number from being set to 0x0000. To produce a16-bit device ID value, for example, four zeros can be used for the fourmost significant bits of the sequence. The remaining 24 bits of theoriginal 35 concatenated bits can be used for the sensor security code.

As an example, a given seven character alphanumeric ID, ‘A65834F’, isconverted to binary as follows using the binary mappings shown in FIG.6A,

A=01010

6=00110

5=00101

S=11010

3=00011

4=00100

F=01111

These binary values are concatenated to produce a 35 bit sequence:

01010001100010111010000110010001111

This 35 bit sequence is then separated to produce:

01010001100 and 010111010000110010001111

The device ID becomes 0000 0101 0001 1001 after a one is added as theleast significant bit, and four zeros are added as the most significantbits. The other 24 bits are padded on the left with eight zeros tobecome the four byte value 0000 0000 0101 1101 0000 1100 1000 1111.

Therefore, the device ID becomes the two byte array [0x05][0x19] used asdescribed above in the low level standardized communication protocol.The sensor security code becomes the four byte array[0x00][0x5D][0x0C][0x8F], used as described below.

When the analyte sensor system 8 is initially set up, the identifierassociated with the system is entered into the display device 14, 16,18, 20. Now, the sensor system 8 and the display device 14, 16, 18, 20can each compute the same device ID and sensor security code using thealgorithm described above.

FIG. 7 is a flowchart illustrating one embodiment of an aspect of aprocess for pairing a transmitter with a receiver using a device ID andsensor security code. In block 702, the transceiver in the sensor system8 sends one or more message beacons that include the device ID and achallenge value used in conjunction with the sensor security code aswill be described below. In block 704, the display device 14, 16, 18, 20may receive the transmission and determine whether to pair with thesensor system 8 by checking for a match between the device ID in thereceived beacon and the device ID it is searching for. If the device IDdoes not match, the pairing process can end, as shown in block 714. Ifthe device ID does match, a communication channel is established. Thepart of the communication process involved in establishing acommunication channel may be handled by the transceiver circuitry 316,338 in accordance with the protocols established for the standardizedcommunication and embedded in the transceiver circuitry. The processor330 need not manage or even be aware of received beacons that do notcontain the appropriate device ID.

If a communication channel is established, the challenge value isprovided to the processor 330 to perform an additional authenticationprocess as will now be described. The display device 14, 16, 18, 20processes the challenge value using a predetermined algorithm and thesensor security code to produce an authentication response value asshown in block 706, as well as generating a request for sensor data. Inblock 708, a hashed value that includes the authentication responsevalue as other information as described below is transmitted back to thesensor system 8 along with the request for sensor data. Sending a hashedvalue may avoid ever sending analyte sensor system 8 or display device14, 16, 18, 20 identity information directly. In block 710, the sensorsystem 8 receives and verifies the hashed value including theauthentication response value sent by the display device 14, 16, 18, 20using the same algorithm and sensor security code. If the authenticationresponse value is valid, the sensor system 8 transmits the requestedsensor data to the display device 14, 16, 18, 20 as shown in block 712.Otherwise, as shown in block 714, the pairing process can end.

By using the method described with both the device ID and a sensorsecurity code for communication authentication, two benefits can beobtained. First, security can be improved over using the device ID aloneas authentication, because one weak link in device ID security is thatthe device ID is transmitted over the air in the message beacons. Whenthe device ID is transmitted over the air, it could be intercepted by ahacker or other unauthorized user, and used to create a false receiverthat could query the sensor system for user data. In addition,computational efficiency can be improved because devices withoutmatching device IDs need not authenticate with a receiver device usingthe challenge/response protocol before discovering that no communicationchannel should be opened between the devices. Primary and SecondaryDisplay Devices

In some cases, the type of data exchanged between the analyte sensorsystem 8 and the display device 14, 16, 18, 20 may depend on the type ofdisplay device 14, 16, 18, 20. For example, some display devices 14, 16,18, 20 may be configured to communicate calibration data to an analytesensor system 8 and may have additional functionality for initiating newsensor sessions, setting certain alert thresholds and the like. Such adevice may be referred to as a “primary” display device. In some cases,the primary display device may correspond to the device speciallyconfigured for use with the analyte sensor system 8 by a manufacturer.The primary display device may be used to configure and set up each newsensor session after sensor components have been replaced.

In some embodiments, other display devices may have less functionalityand may be provided by generic electronic devices includingcommunication circuitry that may communicate with the analyte sensorsystem 8 using an established base communication protocol. These displaydevices may be referred to as “secondary” devices, and may includegeneral purpose smart phones, smart sports watches, general purposetablet computers, etc. The secondary display devices may not bepermitted to communicate calibration data with the analyte sensor system8 and may be restricted in the type of data that may be requested andreceived. A reason for this may because the secondary display device isnot approved for all of the functionality of a primary device by aregulatory agency, safety, reliability and the like.

In some embodiments, a secondary display device may display analytevalues, display graph or trend arrows, provide audible alerts, orprovide additional ways for providing a user with information aboutglucose measurement values, but not be permitted to provide calibrationinformation to the analyte sensor system 8, for example.

In some embodiments, authentication may depend on the type of displaydevices and the authentication process may allow for detecting the typeof display device.

For illustration purposes only, a primary device may be referred toherein as display device 16 and a secondary display device may bereferred to as to one or display devices 14, 18 and 20 of FIG. 1.

FIG. 8 is flowchart of an exemplary method for establishing anauthenticated communication channel between an analyte sensor system 8and a primary device 16 or a secondary display device 14, 18. In block802, the analyte sensor system 8 transmits a beacon containing achallenge value generated, for example as described above in FIG. 7.This beacon may be received at a primary display device 16 and/orsecondary display device 14, 18 as shown in blocks 804 a and 804 b.

If received at a primary display device 16, the primary display device16 may generate a primary hash value in block 806 a. The primary hashvalue may be generated using a hash algorithm based on one or more of anidentifier of the analyte sensor system 8, a key value, and thechallenge value received in the beacon as shown in block 808 a. Theidentifier may be associated with or derived from a unique identifier,such as an identifier of the analyte sensor system 8 imprinted on ahousing of sensor electronics module 12 as described above.

The hash algorithm may further generate the primary hash value based onother information and identifiers such as an identifier associated withthe primary display device to more easily allow an analyte sensor system8 to determine a display type or the various or limited capabilities ofthe primary display 16.

The analyte sensor system 8 may have a list of allowable displayidentifiers or codes stored in memory. For example, a key value may bespecific to a primary display device 16 type. For example, the key valuemay be a configuration key that is provided in the primary displaydevice 16 by the manufacturer to permit the primary display device 16 tobe used to control and configure the analyte sensor system 8. That is,the use of the configuration key may identify the display device 16 as aprimary display device to the analyte sensor system 8, therebydetermining the type of data exchanged and functionality allowed betweenthe analyte sensor system 8 and the primary display device 16.

The secondary display device 14, 18 may also generate a secondary hashvalue in block 806 b. The secondary hash value may be generated using ahash algorithm based on an analyte sensor system 8 identifier, a keyvalue specific to the secondary display device 14, 18 type, and thechallenge value. The key value may be a “permission” key that isdifferent than the configuration key associated with a primary deviceand may be provided in the secondary display device 14, 18 by themanufacturer or a software supplier of software implemented on thesecondary display device. The permission key may identify the displaydevice 14, 16, 18, 20 as a secondary display device 14, 18 and indicateto the sensor system 8 that the secondary display device 14, 18 haspermission to display glucose data to a user.

In one exemplary environment, there may be multiple different types ofprimary devices and multiple different types of secondary devices thatcan be permitted to communicate with the sensor system 8. Each of thesecondary devices may have different permission keys to identify thetype of the device and accompanying features/limitations that may befacilitated or enforced in part by the analyte sensor system 8 viainstructions stored in the analyte sensor system and executed by aprocessor of the analyte sensor system. The hash algorithm may furthergenerate the secondary hash value based on other information such as adisplay identifier that may provide additional information about thefunctionality of the display to further distinguish between displaydevice 14, 16, 18, 20 types.

In block 808 a and 808 b, after the hash values have been generated, theprimary and secondary display devices 14, 16, 18, 20 may send the hashvalues to the analyte sensor system 8. The analyte sensor system 8 mayalso generate its own hash values for each type of display that theanalyte sensor system 8 is expecting to receive a request from (referredto herein from time to time as “expected hash values”). In this case,the analyte sensor system 8 may generate an expected hash value for aprimary display device 16 and an expected hash value for a secondarydisplay device 14, 18. The expected hash values may be compared to thehash value(s) received from the primary or secondary display device(s),as shown in blocks 810 a and 810 b.

If a received hash value matches none of the expected hash values, thenthe method ends in block 814 and no data is sent by the analyte sensorsystem 8 as the authentication failed. If the received hash valuematches one of the expected hash values, then the communication requestfrom the display device can be considered authenticated and acommunication channel opened between the sensor system 8 and displaydevice and data may be sent between the analyte sensor system 8 theprimary display device 16 or secondary display device 14, 18 as shown inblocks 812 a and 812 b, respectively.

Further to block 812 a and 812 b, once authenticated, the type of dataexchanged between the analyte sensor system 8 and the display device 14,16, 18, 20 may depend on the type of display device (e.g., primary orsecondary). For example, as stated above, in some embodiments theanalyte sensor system 8 can be permitted to request calibrationinformation (e.g., external calibration reference values) from a primarydisplay device 16 but not from a secondary display device 14, 18.Indeed, if calibration data points are received from the display device14, 16, 18, 20 identified as a secondary device, the analyte sensorsystem 8 may refuse or ignore the data. Furthermore, different types ofdata may be exchanged based on the display device 14, 16, 18, 20 type aseach type of display device 14, 16, 18, 20 may have differentlimitations and be configured to display glucose measurement data indifferent ways. Suitable methods and systems for sending different typesof data depending upon the type of display device that can be usedherein are described in further detail in U.S. Patent Publication No.2009/0240120, filed on Feb. 20, 2009, the entire content of which ishereby incorporated by reference.

As discussed above, a configuration key or permission key may be used toidentify a display device as a type of display device (primary orsecondary) or even if the display device is authorized to exchange datawith the sensor system 8. That is, a configuration key or permission canbe associated with a pre-approved device permitted to communicate withthe sensor system. A list of approved keys can be stored in memory ofthe sensor system 8, and if a device attempting to authenticate with thesensor system does not have an approved key, then the device can beprevented from pairing with the sensor system.

In some implementations, multiple different devices can be approved foruse with the sensor system 8. In such a case, the sensor system 8 caninclude multiple keys stored therein; for example, one key for each typeof approved device.

The keys can be stored in a priority order in accordance with someimplementations. During authentication, for example as described withrespect to block 808 in FIG. 13, the sensor system 8 generates hashvalue using a key having the top priority in the key list (e.g., is ontop of the list). If the hash value does not match the hash valuereceived from the display device, then the sensor system generatesanother hash value using the next highest priority vendor code. Theprocess repeats until either there is a match or all of the vendor codesare used without a match. In the latter case, there will be noauthentication between the devices. In one example, the sensor systemcan include 20 different keys. Thus, it is possible that 20 differentkeys may be generated during an authentication.

To facilitate matching of keys, the key priority list can be adaptive.For example, the key that was used to generate a matching hash value canmade the top priority key. That way, during the next authenticationprocess, the key is the first key used to generate the sensor system hasvalue in step 808 of FIG. 8, for example, and if there is a match, thenno further hash values need be generated.

Limiting Communication with Multiple Primary and Secondary DisplayDevices

As described above, the analyte sensor system 8 may reserve just afraction (represented by a data transmission window interval T_(window))of the update interval T_(update) for exchanging data with displaydevices 14, 16, 18, 20. Within this data transmission window intervalT_(window), an analyte sensor system 8 may be able to communicate withmultiple display devices 14, 16, 18, 20. However communicating withmultiple display devices 14, 16, 18, 20 may consume significant amountsof power. Some embodiments may limit the amount of display devices 14,16, 18, 20 that may communicate with the analyte sensor system 8 duringan interval T_(window). In one embodiment, the length of the datatransmission window interval T_(window) may be limited by the analytesensor system 8. In another embodiment, the analyte sensor system 8 mayrefuse requests from display devices 14, 16, 18, 20 once the analytesensor system 8 has already communicated with a predetermined thresholdnumber of display devices (e.g., three display devices during atransmission window T_(window)).

FIG. 9 is a timing diagram showing an exemplary scheme for exchangingdata between an analyte sensor system 8 and a plurality of displaydevices 14, 16, 18. The analyte sensor system 8 may be configured tosend and receive data during specified time slots. During an updateinterval T_(update) (which may be at the beginning or end of theinterval, for example), an analyte sensor system 8 may begintransmitting beacons as described above. A primary display device 16 maysuccessfully receive the beacon (e.g., after the analyte sensor system 8sends out two beacons as illustrated in FIG. 9) and send a data exchangerequest to the analyte sensor system 8 within the third time slot of theprimary device's timing diagram. Once the request has been received andthe primary display device 16 has been authorized, data may be exchangedbetween the two devices as indicated by the shaded time slots. As anillustrative example, the data in the first data time slot may includethe most recent glucose measurement values and data in subsequent timeslots may include calibration data or other control or configurationdata. Once the analyte sensor system 8 and the primary display device 16have finished exchanging requested data, the communication channel withthe may be closed.

If there is still time remaining in the data transmission windowinterval T_(window), the analyte sensor system 8 may resume sendingbeacons. As shown in FIG. 9, a first secondary display device 14 may beattempting to communicate with the analyte sensor system 8 and beginlooking for the beacon at the beginning of T_(window). In this case,while the first secondary display device 14 may receive the beacon atthe same time as the primary display device 16, the analyte sensorsystem 8 may ignore subsequent requests from the first secondary displaydevice 14 if it is already communicating with a primary display device16. As will be further described below, in some embodiments, the type ofdisplay device may not be a factor in determining who first establishesthe communication channel. Rather, in one embodiment, the display devicethat responds to the beacon first will be able to establish thecommunication channel and other devices may have to wait. As such, withreference to FIG. 9, if the first secondary display device 14 respondsto the beacon before the primary display device 16, then a channel wouldbe established initially with the first secondary display device 14. Ifthe primary display device 16 responds first, the first secondarydisplay device 14 may continue to listen for a beacon from the analytesensor system 8 until it is authenticated by the analyte sensor system 8and a channel is established between the analyte sensor system 8 and thefirst secondary display device 14. As shown in FIG. 9, the firstsecondary display device 14 may receive a beacon and establish a channelafter the analyte sensor system 8 has finished communicating with theprimary display device 16. The first secondary display device 14 maythen exchange data with the analyte sensor system 8 for one or more timeslots and subsequently close the channel.

If there is time remaining in the transmission window after finishingcommunicating with the first secondary display device 14, then theanalyte sensor system 8 may resume sending beacons.

A second secondary display device 18 may additionally be attempting tocommunicate with the analyte sensor system 8 and begin searching toacquire a beacon during T_(window). The second secondary display device18 may continuously look for the beacon until the analyte sensor system8 finally acknowledges and authenticates the second secondary displaydevices 18 after communicating with the primary display device 16 andthe first secondary display device 14. Once authenticated, the secondsecondary display device 18 may exchange data with the analyte sensorsystem 8 and close the channel. This process may continue with otherdisplay devices 20 until a specified communication interval T_(window)ends and the analyte sensor system 8 stops sending beacons until thebeginning of another transmission window (e.g. at the beginning of thenext update time interval T_(update)).

To conserve power, the number of display devices to which the analytesensor system 8 communicates may be limited in several ways. Forexample, the analyte sensor system 8 may stop transmitting beacons orresponding to data exchange requests after exchanging data with apredetermined number of display devices 14, 16, 18, 20. For example, theanalyte sensor system 8 may only be allowed to communicate with amaximum of three devices during each data transmission window intervalT_(window).

The maximum number of display devices that can communicate during atransmission window interval can be variable. The variable can be setduring manufacturing of sensor electronics module 12, can be userconfigurable by using display device 14, 16, 18, 20, for example, or canbe automatically adjusted by sensor system 8 or display device 14, 16,18, 20 based on one or more criteria. The criteria can include amonitored battery level of the analyte sensor system 8. For example, ifthe battery level is below a threshold, the analyte sensor system 8 maybe configured to only communicate with one display device 14, 16, 18,20. The criteria can include: (i) one or more errors detected by sensorsystem 8 or display device 14, 16, 18, 20, (ii) a currently measured,previously measured and/or predicted glucose concentrations meeting orexceeding a predetermined threshold, (iii) a glucose concentration trendof the host based on currently measured, previously measured and/orpredicted glucose concentrations, (iv) a rate of change of glucoseconcentration of the host based currently measured, previously measuredand/or predicted glucose concentrations meeting or exceeding apredetermined threshold, (v) whether the host is determined to be in ornear hyperglycemia based on currently measured, previously measuredand/or predicted glucose concentrations, (vi) whether the host isdetermined to be in or near hypoglycemia based on currently measured,previously measured and/or predicted glucose concentrations, (vii) userinputted activity of the host (e.g., exercising or sleeping), (viii)time since a sensor session has started (e.g., when a new sensor 10 isused), and (ix) type of display device.

In addition, limiting communication based on the battery level may bedone by shortening the transmission window T_(window), restricting thetypes of devices that may communicate with the sensor system, limit thetypes of data that can be exchanged between the sensor system anddisplay devices 14, 16, 18, 20, or the like.

It should be appreciated that while the above functionality has beendescribed with respect to dividing and restricting communication basedon time slots, the principles described herein may apply to othercommunication protocols that use other multiplexing techniques such asfrequency division multiplexing.

Furthermore, while FIG. 9 shows first communicating with a primarydisplay device 16 and then two secondary display devices 14, 18, itshould be appreciated that the order and type of display devices may notmatter. As such, the analyte sensor system 8 may communicate first witha secondary display device 14 and then with a primary display device 16.In some embodiments, the analyte sensor system 8 may communicate onlywith a primary display device 16 during the communication intervalT_(primary). In other embodiments, the analyte sensor system 8 maycommunicate with only secondary display devices 14, 18 during thecommunication interval T_(secondary).

In some cases it may be important to always allow a primary displaydevice 16 to communicate during a transmission window. As such, theanalyte sensor system 8 may implement a priority scheme to ensure theanalyte sensor system 8 communicates with a primary display device 16during the transmission window. In one embodiment, the analyte sensorsystem 8 may establish a specified time interval (T_(primary)) reservedfor communication with a primary display device 16 within thetransmission window interval T_(window). In T_(primary), which may be atthe beginning of the transmission window T_(window), the analyte sensorsystem 8 may be configured to only respond to and authenticate with aprimary display device 16 and ignore other requests. After theT_(primary) interval expires, secondary display devices 14, 18 may havethe opportunity to establish a channel in addition to the primarydisplay device.

It may be further necessary to restrict the use of a secondary displaydevice 14, 18 when a primary display device 16 is capable of exchangingdata with an analyte sensor system 8. For example, the primary displaydevice 16 may incorporate functionality such as special alerts or alarmsthat help to ensure that a user maintains safe glucose levels.Regulations or safety guidelines may therefore require that the primarydisplay device 16 always be used. As such, to help ensure the primarydisplay device 16 is being used, the analyte sensor system 8 may onlyallow communication with a secondary display device 14, 18 if theanalyte sensor system 8 has already sent glucose information to aprimary display device 16 in a given transmission window T_(window).

When sensor components are replaced (e.g. a new sensor 10 used in sensorsystem 8), a new sensor session may be established. In some embodiments,communication of glucose values to secondary devices 14, 18 may bedisallowed until initiating of the sensor session is performed between aprimary display device 16 and sensor system 8. The initiation processmay include providing calibration data and setting alert thresholds forthe sensor session. Once the session has been initiated using a primarydisplay device 16, secondary display devices 14, 18 may be allowed toexchange data with the sensor system 8, such as receive glucosemeasurements and perform various functions (e.g., display estimatedglucose values (EGVs), trend graphs, arrows, sound alarms) even if theprimary display device 16 is not currently in proximity to or exchangingdata with the analyte sensor system 8. However, certain functionality ofthe secondary display device 14, 18 may be restricted. As such,communication between the secondary display device 14, 18 and theanalyte sensor system 8 may be based on communication between theprimary display device 16 and the analyte sensor system 8. In anotherembodiment, the analyte sensor system 8 may not actively measure glucoseconcentration values until the sensor session is initiated with aprimary display device 16. In this case, the analyte sensor system 8 maynot transmit any information and a secondary display 14, 18 would not beable receive any information or establish a channel. In this case, asecondary display device 14, 18 would not be able to communicate untilthe sensor session was initiated by a primary display device 16.

FIG. 10 is a flowchart of an exemplary method for communication betweenan analyte sensor system 8 and a secondary display device 14, 18. Inblock 1002, an analyte sensor system 8 may receive a request for sensordata from a secondary display device 14, 18 during a transmissionwindow. In block 1004, the analyte sensor system 8 may determine whethera communication channel been established between the analyte sensorsystem 8 and a primary display device 16 during the transmission window.If no communication channel was established with a primary displaydevice 16, then the method may end in block 1010 and the analyte sensorsystem 8 may refuse to communicate with the secondary display device 14,18. For example, if a period of time of the transmission window isreserved for communication with a primary display device 16 and nocommunication takes place, any subsequent requests by secondary displaydevices 14, 18 may be refused. If a communication channel has beenestablished with a primary display device 16 during the transmissionwindow, then the analyte sensor system 8 may authenticate and establisha communication channel with the secondary display device 14, 18 asshown in block 1006. In block 1008, the analyte sensor system 8 may thentransmit sensor data to the secondary display device 14, 18.

Active Primary Display Device Determination

In some embodiments, while many display devices may be permitted tocommunicate with sensor electronics module 12, it may be desirable tolimit use of primary display devices with a sensor electronics module toone at any given time. Some embodiments provide rules to determine if agiven primary display device is currently the active primary displaydevice. If a user tries to perform any action from a non-activecontroller, the user may be informed that the device is not currentlythe active primary display device and presented instructions via thedevice to make the device the active controller. Switching activeprimary devices may be desirable if the user loses the active primarydevice or wants to switch to a newer primary display device, forexample.

The following is one implementation of an active controllerdetermination process. Here, the sensor system 8 maintains an identifier(“primary display device id”) specific to the currently active primarydisplay its memory. During an established communication channel with thesensor system 8, the primary display device may request from the sensorsystem the currently active primary display id. In one implementation,the primary device requests an alerts data page that includesinformation indicative of current alert settings as well as the activeprimary display id stored in the sensor system. If the primary displaydevice id in the message indicates that the sensor system 8 has beenalready communicating with a primary display (indicated by anon-matching primary display device id) or if no other primary displaydevice has been in communication (indicated by all zeros for the id, forexample), the primary display will display instructions to the user toconfirm if the user intends to make this display device the new activeprimary display device. If the user confirms, the primary display devicegenerates a new two byte random id and sends that to the sensor system 8as the primary display device id and the sensor system switches to thenew primary display device id.

After switching to a new primary display device id, the sensor system 8sends a message indicative of the change for a predetermined number ofsubsequent window beaconing cycles, such as three beacon cycles. Themessage may be a predetermined bit within the data page of each beaconindicating the change. A primary display device that receives themessage may request the primary display device id stored in the sensorsystem from the sensor system and compare the received primary displaydevice id to the primary device id stored in its own memory. If theprimary display id from the sensor system does not match its own primarydisplay id, then the primary display can display instructions to theuser indicating this change and make itself into a non-active primarydisplay. In an implementation, a non-active primary display will thenonly have the functionality of a secondary display device. If the userneeds to start using this display as an active primary display again,the user may perform a fresh pairing with the sensor system 8 asdiscussed above.

In some implementations, if a primary display misses more than apredetermined number of beacon cycles, such as three beacons cycles, theprimary display device will then automatically confirm that it is stillthe active primary display device using the above-described process.

Display Device Handoff

As the data transmission window interval T_(window) of an analyte sensorsystem 8 may only be a small fraction (e.g., 30 seconds) of a muchlonger update interval (e.g., five minutes), it may be desirable for adisplay device 14, 16, 18, 20 to have specific information about thetime when T_(window) opens to know when to listen for the beacon sent bythe analyte sensor system 8.

As described above, when the sensor electronics module is firstactivated (e.g., when it is powered for the first time or after abattery replacement), there may be a process completed using a primarydisplay device 16 to establish communications and synchronize the timingof later transmission windows. For example, upon activation, thetransceiver 316 may initially continuously emit beacons or enter thetransmission window more frequently until communication is establishedwith a primary display device 16. In this way the primary display device16 may not need specific information about when the transmission windowT_(window) opens. Once the channel is initially opened, the analytesensor system 8 may send synchronization information to the primarydisplay device 16, or synchronization information may be derived basedon the timing of beacon transmissions, so that the primary displaydevice knows when the transmission window T_(window) will be open. Theprimary display device 16, may therefore be able to know the timing forestablishing communication with the analyte sensor system 8 over thelife of the battery (and over several sensor sessions).

The synchronization information may not be initially available to asecondary display device 14, 18; for example, if the secondary device14, 18 has not yet established communication with the sensor system. Insuch a case, the secondary display device 14, 18 may not know when atransmission window starts and consequently search for beacons at thewrong time. This can cause the secondary display device 14, 18 to missthe opportunity to establish a communication channel with the sensorsystem 8 during the transmission window. As such, some embodiments allowthe secondary device to learn transmission window synchronizationinformation. The primary display device 16 may provide thesynchronization information to the secondary display device 14, 18.

In one embodiment, the display of the primary display device 16 maydisplay an indication of the time remaining until the next transmissionwindow of the analyte sensor system 8 opens based on the synchronizationinformation previously gathered from the sensor system and now stored inthe primary display device. The indication can be a graphical indicationof a timer (graphical bar, pie chart, etc.) timing down to when thewindow is scheduled to open next, or can be a numerical timerincrementing the time left until the window is scheduled to open next. Auser of a secondary display device 14, 18 may monitor the time remainingand then provide an input to the secondary display device 14, 18 (e.g.,press a button or other activation trigger) when the transmission windowof the analyte sensor system 8 is about to open. The user input mayactivate the secondary display device 14, 18 to begin searching for abeacon.

In another embodiment, the primary display device 16 may electronicallypass off sensor system synchronization information to the secondarydisplay device 14, 18 via wired or wireless communication. FIG. 11 is aflow chart of an exemplary method for providing sensor systemsynchronization information from primary display device 16 to asecondary display device 14, 18. In block 1102, the primary displaydevice 16 may receive a beacon from an analyte sensor system 8.Synchronization information about the timing of the transmission windowof the analyte sensor system 8 (e.g., the time of the beginning of eachdata transmission window interval T_(window)) may be included in orderived from the beacon. In block 1104, a communication channel may beestablished between the primary display device 16 and a secondarydisplay device 14, 18 that wants to obtain the timing information forestablishing a communication channel with the analyte sensor system 8.In block 1106, the primary display device 16 may then send beaconinformation to the secondary display device 14, 18 that may includetiming information for establishing a communication channel with theanalyte sensor system 8. The beacon information may include the currenttransmission time (e.g., from the point at which the primary displayopened its channel) and an update interval equal to the amount of timeremaining until the glucose device's next transmission. In addition,further information may be exchanged between the secondary displaydevice 14, 18 and the primary display device 16 such as past glucosedata information that may be stored on the primary display device 16.

Once the secondary display device 14, 18 has received the beaconinformation, the secondary display device 14, 18 may then establish acommunication channel with the analyte sensor system 8 based on thebeacon information as shown in block 1108. Moreover, in someembodiments, an authentication procedure, similar to the authenticationprocedure described above, may be used between the primary displaydevice 16 and the secondary display device 14, 18 to establishcommunication in block 1104.

While the above description primarily describes a handoff from a primarydevice to a secondary display device, it is understood that thisdescription is illustrative only, and that the handoff can likewise bebetween a first primary display device and a second primary displaydevice, should a new primary display device be desired to be used.Similarly, the handoff can be performed between to secondary displaydevices in some implementations.

Interleaving Transmission and Measurement Sessions

The more operations that are performed substantially simultaneously onthe analyte sensor system 8, the more power may be consumed during thattime. For example, significant power consumption may occur if theanalyte sensor system 8 is transmitting sensor data during the same timethat the analyte sensor system 8 is sampling and/or processing sensorreadings. To reduce strain on battery usage or the need to use a batterythat can provide large amounts of power at a given time, someembodiments interleave transmission and measurement sessions to avoidsimultaneously transmitting while taking measurement and processing themeasurements. This may dictate that the analyte sensor system 8transmits only between sessions where sampling of sensor data and anysubsequent processing is performed. In addition, the amount of time ofthe transmission window may be limited to ensure that it does notoverlap with sampling and processing.

FIG. 12A is a timing diagram of an exemplary timing scheme fortransmitting data and obtaining and processing analyte sensormeasurements. As shown in FIG. 12A, each update interval T_(update) maybe divided into two periods: a sensor measurement and processing period1220 a, 1220 b and a data communication period 1230 a, 1230 b. If theT_(update) interval is five minutes, then a four minute and 30 secondmeasurement cycle 1220 a may be followed by a thirty second transmissionwindow 1230 a, for example. Measurement circuitry 310 may be powereddown during the transmission window 1230 a and the transceiver 316 maybe powered down during a measurement cycle 1220 a. This may be repeatedfor each update interval.

In some cases the length of time of the measurement cycles 1220 mayvary. In these cases the length of time of the transmission window 1230may be adjusted to ensure it does not overlap with the measurementcycle. Further, the analyte sensor system 8 may send information in thebeacons about the total length of time the current transmission windowwill be open or how much time remains until the current transmissionwindow closes.

FIG. 12B is a flowchart of an exemplary method for interleaving ananalyte sensor measurement and processing period with a datacommunication period for transmitting glucose measurement values. Inblock 1202, the analyte sensor system 8 may activate sensor measurementcircuitry 310 and deactivate the transceiver 316 during a first timeinterval. In block 1204, the analyte sensor system 8 may obtain andprocess sensor readings during the first time interval. Once thesampling and processing is completed, the analyte sensor system 8 maydeactivate the sensor measurement circuitry 310 and activate thetransceiver 316 during a second time interval corresponding to a datatransmission window. In block 1208, the analyte sensor system 8 may thentransmit sensor data during the second time interval to a display device14, 16, 18, 20. This process may be continuously repeated for eachupdate interval.

It should be appreciated that a full time interval may not be needed forsensor measurement and processing. As such, the measurement circuitry310 may further be deactivated for the portion of the time interval thatit is not being used. Accordingly, the activating and deactivating inFIG. 12 B may include selectively powering down/up some or all of thesensor measurement circuitry 310 and transceiver 316, or selectivelyplacing the sensor measurement circuitry 310 and transceiver 316 into alow power mode such as a sleep mode.

Providing Missing Data to a Display Device

An analyte sensor system 8 may continuously store past glucosemeasurements. A display device 14, 16, 18, 20 may not always have thefull history of glucose data stored on the analyte sensor system 8. Forexample, the display device 14, 16, 18, 20 may have been out of range ofthe analyte sensor system 8 for a time period or is being newly used inthe middle of a sensor session and wants to access the missing datastored on the analyte sensor system 8.

FIG. 13A shows an example of data structures 1310 a, 1310 b, and 1310 cthat may be stored on an analyte sensor system 8 that include glucosemeasurement values. The data structures 1310 a, 1310 b, and 1310 c maybe formatted as data files, each with a series of glucose measurementvalues. The data structures 1310 a, 1310 b, and 1310 c may hold glucosemeasurement values that correspond to a specific time period over whichthe stored glucose measurement values were obtained. For example, eachdata structure 1310 a, 1310 b, and 1310 c may correspond to atwenty-four hour period of glucose measurements.

One embodiment of the invention provides for allowing the display device14, 16, 18, 20 to request and receive past glucose measurements from theanalyte sensor system 8 in addition to the normal transmission of themost recent glucose measurement value.

FIG. 13B is a flowchart of an exemplary method of transmitting sensordata from an analyte sensor system 8 to a display device 14, 16, 18, 20.The display device 14, 16, 18, 20 may be able to determine a range ofmissing glucose measurement-related data that it desires from theanalyte sensor system 8. In block 1302, an analyte sensor system 8 mayreceive a request for previous glucose measurement values 1312 inaddition to glucose measurement value normally included in the periodicdata transmission. In block 1304, the analyte sensor system 8 may thentransmit a data set corresponding to some time interval over whichmeasurement values are stored that includes the requested glucosemeasurement values. The analyte sensor system 8 may be formattedspecially for transmission (e.g., a compressed). In one aspect, anentire data set 1310 a (e.g., a data file) may be transmitted as opposedto just the requested range of glucose measurement related data. Assuch, the transmitted data set 1310 may include a range of glucosemeasurement related data that exceeds the requested range. This mayreduce processing time and power needed to retrieve and send only thespecifically requested range of glucose measurement related data. Thismay provide for significant power savings which may allow the battery ofsensor system 8 to last longer.

Furthermore, as described above, a primary display device 16 may also beconfigured to provide missing data values to a secondary display device14, 18 to avoid wasting processing power on the analyte sensor system 8to transmit the missing data points.

Technical Support Data Exchange

In some implementations, the sensor system may monitor and recordpossible technical issues associated with the sensor system 8. Thetechnical issues may be recorder in a technical support log file storedin memory of the sensor system

A user of the sensor system 8 may recognize a problem or otherwisedetermine a need to contact technical support to resolve the problem orneed. At that time, the technical support may want the user to obtainsome or all of the technical support log file from the sensor system 8.However, since the sensor system 8 may not have a display and a displaydevice may only be able to communicate with the sensor systeminfrequently (only when the next transmission window opens), the usermay have to wait a significant amount of time before being able toobtain the technical support log file from the sensor system and displayinformation in the file on the display device or transmit (for exampleover the Internet) some or all of the technical file log from thedisplay device to a computer associated with the technical support.

In addition, it may be desirable to collect sensor data and/or thetechnical support log file to support analysis of sensors or debuggingof the sensor system software or firmware. In these situations, it maybe desirable to be able to collect this information without annoying theuser (for example, by not requiring the user to press buttons fordownloads).

In some implementations, the sensor system 8 can send a message to adisplay device anytime the sensor system determines that technicalsupport information stored in the technical support log file is worthhaving on the display device. For illustrative purposes, such anoccurrence can include: (i) the sensor system going out of calibrationafter a calibration; (ii) the sensor system not going out ofcalibration, but the difference between a reference value and acorresponding estimated glucose value exceeds a predetermined amount;(iii) the sensor system software or firmware encounters a particulartype of error, even if the system determines that it has resolved theerror; (iv) the sensor system firmware or software encounters an errorthat results in alerting the user to the error via the display device;and (v) periods of time during use of a sensor where the sensor systemdetects noise or other kinds of aberrations above a predetermined level.

When the display device receives the message, it can be programmed toautomatically request some or all of the support file log. The displaydevice may also automatically send the support log file to the technicalsupport computer over a communication network (e.g., cellular network isthe display device is a smart phone or over the Internet if the displaydevice is a PC connected to the Internet). If a communication network isnot immediately available, the display device can send the support logfile technical support upon connecting to the display device to suitablecommunication network. This way, the display device and/or technicalsupport may already have the technical information on hand when a usercalls technical support to resolve a problem or need.

In some embodiments, the message sent by the sensor system is a bit in adata page sent from the sensor system indicative of the presence of thetechnical support information. The data page is the beacon data page insome implementations. Having the bit can provide the flexibility toobtain the technical support data without having to specify all theconditions under which the display device needs to obtain the technicalsupport log file. For example, the display device can also choose not toobtain the technical support log file from the sensor system if similarconditions occurred in the recent past and technical support was alreadyperformed the previous time.

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Methods and devices that are suitable for use in conjunction withaspects of the preferred embodiments are disclosed in U.S. patentapplication Ser. No. 09/447,227 filed Nov. 22, 1999 and entitled “DEVICEAND METHOD FOR DETERMINING ANALYTE LEVELS”; U.S. patent application Ser.No. 11/654,135 filed Jan. 17, 2007 and entitled “POROUS MEMBRANES FORUSE WITH IMPLANTABLE DEVICES”; U.S. patent application Ser. No.11/654,140 filed Jan. 17, 2007 and entitled “MEMBRANES FOR AN ANALYTESENSOR”; U.S. patent application Ser. No. 11/543,396 filed Oct. 4, 2006and entitled “ANALYTE SENSOR”; U.S. patent application Ser. No.11/543,490 filed Oct. 4, 2006 and entitled “ANALYTE SENSOR”; U.S. patentapplication Ser. No. 11/543,404 filed Oct. 4, 2006 and entitled “ANALYTESENSOR”; U.S. patent application Ser. No. 11/691,426 filed Mar. 26, 2007and entitled “ANALYTE SENSOR”; U.S. patent application Ser. No.11/691,432 filed Mar. 26, 2007 and entitled “ANALYTE SENSOR”; U.S.patent application Ser. No. 11/691,424 filed Mar. 26, 2007 and entitled“ANALYTE SENSOR”; and U.S. patent application Ser. No. 11/691,466 filedMar. 26, 2007 and entitled “ANALYTE SENSOR”.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such illustration and descriptionare to be considered illustrative or exemplary and not restrictive. Thedisclosure is not limited to the disclosed embodiments. Variations tothe disclosed embodiments can be understood and effected by thoseskilled in the art in practicing the claimed disclosure, from a study ofthe drawings, the disclosure and the appended claims.

All references cited herein are incorporated herein by reference intheir entirety. To the extent publications and patents or patentapplications incorporated by reference contradict the disclosurecontained in the specification, the specification is intended tosupersede and/or take precedence over any such contradictory material.

Unless otherwise defined, all terms (including technical and scientificterms) are to be given their ordinary and customary meaning to a personof ordinary skill in the art, and are not to be limited to a special orcustomized meaning unless expressly so defined herein. It should benoted that the use of particular terminology when describing certainfeatures or aspects of the disclosure should not be taken to imply thatthe terminology is being re-defined herein to be restricted to includeany specific characteristics of the features or aspects of thedisclosure with which that terminology is associated. Terms and phrasesused in this application, and variations thereof, especially in theappended claims, unless otherwise expressly stated, should be construedas open ended as opposed to limiting. As examples of the foregoing, theterm ‘including’ should be read to mean ‘including, without limitation,’‘including but not limited to,’ or the like; the term ‘comprising’ asused herein is synonymous with ‘including,’ ‘containing,’ or‘characterized by,’ and is inclusive or open-ended and does not excludeadditional, unrecited elements or method steps; the term ‘having’ shouldbe interpreted as ‘having at least;’ the term ‘includes’ should beinterpreted as ‘includes but is not limited to;’ the term ‘example’ isused to provide exemplary instances of the item in discussion, not anexhaustive or limiting list thereof; adjectives such as ‘known’,‘normal’, ‘standard’, and terms of similar meaning should not beconstrued as limiting the item described to a given time period or to anitem available as of a given time, but instead should be read toencompass known, normal, or standard technologies that may be availableor known now or at any time in the future; and use of terms like‘preferably,’ ‘preferred,’ ‘desired,’ or ‘desirable,’ and words ofsimilar meaning should not be understood as implying that certainfeatures are critical, essential, or even important to the structure orfunction of the invention, but instead as merely intended to highlightalternative or additional features that may or may not be utilized in aparticular embodiment of the invention. Likewise, a group of itemslinked with the conjunction ‘and’ should not be read as requiring thateach and every one of those items be present in the grouping, but rathershould be read as ‘and/or’ unless expressly stated otherwise. Similarly,a group of items linked with the conjunction ‘or’ should not be read asrequiring mutual exclusivity among that group, but rather should be readas ‘and/or’ unless expressly stated otherwise.

Where a range of values is provided, it is understood that the upper andlower limit, and each intervening value between the upper and lowerlimit of the range is encompassed within the embodiments.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity. The indefinite article “a” or “an” does not exclude aplurality. A single processor or other unit may fulfill the functions ofseveral items recited in the claims. The mere fact that certain measuresare recited in mutually different dependent claims does not indicatethat a combination of these measures cannot be used to advantage. Anyreference signs in the claims should not be construed as limiting thescope.

It will be further understood by those within the art that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

All numbers expressing quantities of ingredients, reaction conditions,and so forth used in the specification are to be understood as beingmodified in all instances by the term ‘about.’ Accordingly, unlessindicated to the contrary, the numerical parameters set forth herein areapproximations that may vary depending upon the desired propertiessought to be obtained. At the very least, and not as an attempt to limitthe application of the doctrine of equivalents to the scope of anyclaims in any application claiming priority to the present application,each numerical parameter should be construed in light of the number ofsignificant digits and ordinary rounding approaches.

Furthermore, although the foregoing has been described in some detail byway of illustrations and examples for purposes of clarity andunderstanding, it is apparent to those skilled in the art that certainchanges and modifications may be practiced. Therefore, the descriptionand examples should not be construed as limiting the scope of theinvention to the specific embodiments and examples described herein, butrather to also cover all modification and alternatives coming with thetrue scope and spirit of the invention.

What is claimed is:
 1. A method for transmitting data between a firstcommunication device associated with an analyte sensor and a secondcommunication device configured to provide user access to analyte valuesand/or information derived from analyte values, comprising: activating atransceiver of a first communication device associated with an analytesensor at a first time; establishing a two-way communication channelwith the second communication device using an authentication scheme;sending analyte sensor data to the second communication device using thetwo-way communication channel; deactivating the transceiver of the firstcommunication device at a second time; and periodically repeating theactivating, establishing, sending and deactivating, wherein a differencebetween the first time and the second time is less than or equal to oneminute, and wherein the periodic repeating is performed at least onceevery 30 minutes.
 2. The method of claim 1, wherein activating comprisessupplying power to the transceiver, and wherein deactivating comprisespowering down the transceiver.
 3. The method of claim 1, whereinactivating comprises waking the transceiver from a low power sleep mode,and wherein deactivating the transceiver comprises placing thetransceiver into a lower power sleep mode.
 4. The method of claim 1,further comprising closing the two-way communication channel beforedeactivating the transceiver.
 5. The method of claim 1, wherein thedifference between the first time and second time corresponds to atransmission time window, and wherein the analyte sensor datacorresponds to a new glucose measurement obtained prior to a beginningof the time window, and wherein beginnings of successive time windowsare separated by an update time interval.
 6. The method of claim 1,further comprising periodically measuring an analyte sensor value beforeeach of the periodic repeating the activating, establishing, sending,and deactivating.
 7. The method of claim 6, wherein the analyte sensorvalue comprises a glucose concentration.
 8. A system for monitoring ananalyte level of a host, the system configured to perform the method ofclaim 1, wherein the system comprises a sensor electronics moduleincorporating a transceiver, the sensor electronics module configured toelectronically couple to an analyte sensor and generate an analyte datastream using the analyte sensor.
 9. A method for authorizing analytesensor data exchange between a first communication device associatedwith an analyte sensor and a second communication device configured toprovide user access to analyte values and/or information derived fromanalyte values, comprising: sending a challenge value from a firstcommunication device associated with an analyte sensor to a secondcommunication device; generating a first hash value in the secondcommunication device using, at least in part, one or more of thechallenge value, an identifier of the first communication device, or akey value; sending the first hash value from the second communicationdevice to the first communication device; generating, using the firstcommunication device, a second hash value and a third hash value;comparing, using the first communication device, the second hash valueand the third hash values to the first hash value; and sending analytesensor data only if at least one of the second hash value or the thirdhash values matches the first hash value.
 10. The method of claim 9,further comprising determining a type of the second communication devicebased on a match between the first hash value and the second hash valueor a match between the first hash value and the third hash value. 11.The method of claim 9, wherein the key value is a first value if thesecond communication device is of a first type, and wherein the keyvalue is a second value if the second communication device is of asecond type.
 12. The method of claim 11, wherein the type of seconddevice corresponds to one of a primary device or a secondary device,wherein the primary device is configured to communicate analytecalibration data to the first communication device, and wherein thefirst communication device is configured to reject analyte calibrationdata received from a secondary communication device.
 13. The method ofclaim 9, wherein the first hash value is generated using a displayidentifier.
 14. The method of claim 10, wherein sending analyte sensordata comprises sending analyte sensor data based at least in part on thetype of the second communication device.
 15. A system for monitoring ananalyte level of a host, the system configured to perform the method ofclaim 9, wherein a first communication device comprises a sensorelectronics module, and wherein the sensor electronics module isconfigured to electronically couple to an analyte sensor and to generatean analyte data stream using the analyte sensor.
 16. A method fortransmitting data between a first communication device associated withan analyte sensor and one or more second communication devicesconfigured to provide user access to analyte values and/or informationderived from analyte values, comprising: receiving a request from asecond communication device of the one or more second communicationdevices to establish a channel for receiving analyte sensor data fromthe first communication device during a transmission window; andestablishing a communication channel between the first communicationdevice and the second communication device if a number of communicationdevices that previously received analyte sensor data from the firstcommunication device during the transmission window is below athreshold.
 17. The method of claim 16, wherein the second communicationdevice comprises a secondary communication device.
 18. The method ofclaim 16, further comprising: determining whether the secondcommunication device is a primary communication device; andestablishing, if the second communication device is a primarycommunication device, a communication channel with the secondcommunication device even if a number of communication devices thatpreviously received analyte sensor data during the transmission windowis equal to or greater than the threshold.
 19. A system for monitoringan analyte level of a host, the system configured to perform the methodof claim 16, wherein a first communication device comprises a sensorelectronics module, the sensor electronics module configured toelectronically couple to an analyte sensor and to generate an analytedata stream using the analyte sensor.